Hey Laurent, have you by chance opened up Task Manager to see what your GPU/GPU usage is when running just discord and browser tab? The reason I ask is because I just recently had my Framework 16 jump to 100% fan usage out of nowhere when I was literally doing nothing but sitting on the Windows 11 desktop. I opened up Task Manager and noticed my CPU was at 92% usage and it was a bunch of “Windows Module Installer” processes running that didn’t have any associated GUI. I have no idea what they were doing honestly but it reminded me of this thread so I wanted to come back and see if you noticed anything hitting the CPU/GPU hard in task manager when this happened because I think it may not be a bug but rather something in Windows 11 bashing on the CPU really hard in the background causing the sudden need to thermally evacuate heat as fast as possible to prevent thermal throttling. I let the system sit for 5-10 minutes and it eventually ramped back down to being silent and Task Manager confirmed CPU usage was down around 5-10% again.
This obviously won’t solve your problem, but it might give you some information on why the fans are jumping to 100% when you’re doing almost nothing. Next time this happens just open task manager (WIN+SHIFT+ESC) and look at CPU and GPU usage and even sort processes by CPU usage column and see which processes are causing the massive fan speed spike to occur. Because at the end of the day I think the fan speed is just responding to the thermal readings since it’s all controlled by the BIOS and not the OS hence why software like FanControl can’t change the fan curves like it can on a desktop PC or other laptops that allow direct fan control.
If this is the case at least you could then look into ways to potentially thermally throttle those processes down so they can’t use as much CPU perhaps to keep the fans from going to the moon whenever Windows 11 decides the system is idle enough to use all your CPU cycles for something else in the background. But a simple browser tab and discord shouldn’t be beating on your CPU that much. I’m not sure what Foundry VTT is so I couldn’t tell you how hard it hits the CPU since I do know that some websites will use HTML5 code that can make the CPU usage go to the moon but I’m not sure if that site is one of them. TaskManager would clearly show you though if your browser is causing the big CPU hit and even which tab specifically in the browser is causing it if you’re using something like Microsoft Edge where each browser is a separate process under the top-level process. Actually, I think even Chrome does this so either should show you which tab is gobbling up the CPU so much. If you’re able to catch it then you might be able to go into task manager and right click on the process that is beating on your CPU and limit it to a single thread or lower its priority to see if you can’t reduce how much CPU it’s using.
Another option you could try is to go into your Windows 11 Power Options menu and change the Maximum processor state from like 100% to %80 or %50 so that processes can’t hit the CPU as hard which should lower the thermals and prevent the fans from going to the moon in situations where you need quiet over performance like at the coffee shop or office. This isn’t the best solution in the world but it could help you for a while until Framework can give us some kind of option to ramp fan curves and just thermally throttle automatically based on our fan max values, etc. That would be ideal honestly, but in the mean time we might just need to a hack a bit.
If the power thing works for you and keeps the fan noise down by limiting how hard Windows processes can hit your CPU then it would be trivial to build a PowerShell scripts to change the values just by clicking a shortcut on your desktop, etc to change it on and off so you don’t have to keep going deep into these menus to change the values any time you want maximum cooling or maximum quiet options. I hope some of this information helps you on some level! I absolutely love this forum! 
Also, it’s ironic that you’re having problems with cooling noise on your Framework 16 as I’m having problems with my AC in my Nerdcave not kicking off at all no matter what temp it is in the room causing it to freeze up into a block of ice and make the room a giant refrigerator right now. Seems like we’re all having some HVAC related problems in our lives right? 
I’m too cheap to buy a new AC so I think I’m just going to toss a TPLink KASA switch on the AC power and create a script to monitor the room temp using an ESP32 and send a signal to the KASA switch to turn on and off based on the room temperature with a cooldown period so it doesn’t blow up the AC turning it on and off a dozen times a minute. It’s not the perfect solution, but if it works, it works and I can come up with a better solution later! Jerry Rigged BABY! 
Good luck, let me know how things go!
UPDATE:
I just noticed that you said it only seems to do this when connected to DC power in your latest post. This makes me think it’s 100% a thermal issue from your CPU running that is causing the fan speed increase making all the noise. I’d look at what your CPU usage is doing the things you normally do on battery under “task manager” and than take that and set it as your “Maximum CPU State” under the active power profile when plugged into DC and see if that solves the issues once the CPU cools down a little. I suspect if you limit the performance on DC power to the same as it would be on battery you’ll get the same exact fan noise give or take a little. Also, screen brightness shouldn’t affect this much since its heat is dissipated outside of the laptop body and shouldn’t make a difference to the fan speed except for maybe the power supply getting a touch hotter supplying the power. But, on DC you can obviously run fully bright on the screen without risking battery life so you would get to keep that perc even if you lose some CPU performance on DC power to keep the fan speed low. GOOD LUCK! 
Oh, and one more thing, thank you for not running with test signing enabled! I’ve been reading too many horror stories lately about people getting backdoored or losing all their browser cookies with session tokens allowing attackers to take their lives over. It’s just not worth it to run code that Windows is trying to protect you from even if you trust that code since you have to also trust all the other code too. It would be nice if Windows had a conditional test signing that you could enable per process based on checksum signature or something else that is unique, so you don’t have to do all or nothing approach when running test drivers or services.
