Caps lock key issue?
Passwords care case-sensitive. I've often hit a wall logging in with a password because I had last pressed the caps lock, inadvertently or on purpose! If sound is on, it'll beep and that reminds me.
Hope you get it fixed and, if you are able, can set up Touch ID for log-in and other password situations. I never expected it to be such a treat on my M2 MBA!
As to brute force guessing, you could consider possibility likelihood that you reversed two letters or numbers when writing it down — or had capitalized a letter or not that you wrote down differently…. Alternatively, it could be that you didn't type a word, say an “a” or “the”, that you thought you had.
Good wishes for success!