Edit: I can confirm in my case this wasn’t the headphone jack. I just heard the same fluttering noise from the cable that was plugged into the headphone jack, while the laptop was completely unplugged from anything. The power cord was tangled up with the audio cable!
I’ve heard an odd (and nice-sounding) flare-up of intermittent noise from the headphone jack which goes away after a small POP twice since I got my laptop. I didn’t think much of it the first time but the second time I decided to grab my recorder and I got a short recording of it before it went away again. I don’t think it lasted longer than a minute or two altogether.
At the time the laptop was plugged into the power supply that came with it, and I had a raspberry pi 400 mouse plugged into a USB A module on the right bottom side… the audio cable was going straight into a stereo channel on a mixing board and I made the recording from the headphone out on the board.
Anyway it’s not a problem for me at all and I have no idea if this is actually originating from the headphone jack or just some total fluke in my local setup but I thought I’d just share in case it was interesting to anyone! (And I’m curious if anyone else has experienced this too.)