I've seen every new OS update leading to M1 Air performance degrade, at this point I'm pretty convinced Apple is doing this intentionally.
Edit: Same experience with iPhone X
Edit2: I still remember the feeling when I got them initially - that Apple is on customer's side, but now I feel totally helpless and i'm being forced to upgrade
I haven’t noticed this to be honest: macOS 26 Tahoe is the first update that significantly hindered the performances of my MacBook Air M1. Even with the Electron _cornerMask fix + disabling auto heuristics at the OS level.
Edit: Same experience with iPhone X
Edit2: I still remember the feeling when I got them initially - that Apple is on customer's side, but now I feel totally helpless and i'm being forced to upgrade