I was wondering if the issues are related to the fan changes made in the latest Bambu Studio update? The update happened about two weeks ago and that seems to match the timeline of these problems. I don’t know if downgrading Bambu Studio will be enough to revert the fan setting to the previous values, you would have to confirm if the values changed.
This person was having a similar issue with PETG that he determined was caused by the fan speed changes in the latest Bambu Studio update.