I have a 12 gen Windows framework, and after having some loud fan noises, I opened it up (first time) and cleaned off everything I could. Everything was screwed back the way it was.
Now, when I tilted it up the fan suddenly went fulls peed, then shut off, and a few moments later, went back to a normal speed.
this is still going on, would a new Heatsink and Fan Kit (12th Gen Intel® Core™) solve the issue?
100% you should contact support they will help pin down the issue and if you are still in warranty they will send you replacements for any defective parts.
With that said I would try two things before replacement:
Check the fan power plug is fully inserted (for the tilting effecting speed) this is assuming your temperatures are not the reasons for the fan ramping up.
Remove the fan and check for foreign object (for the odd noise). To do this requires removing the motherboard to access the 3 screws on the underside of the fan as well as the two captive screws on the top side and some tape, I just made a post about it here.