same pattern on my M3 Max 16" - Touch ID was solid until somewhere around 26.3, then started degrading. re-enrollment does help but it fades out again over a couple weeks.
one thing I noticed that seems to extend how long it holds: I disabled Apple Watch auto-unlock while re-registering my fingers, and it lasted noticeably longer before reverting. might be coincidence, but worth trying if you haven't. at this point I've just accepted that entering the password is faster than playing the Touch ID lottery.