Macbook login bug: keystrokes not registering consistently during password entry

I’m having an issue when entering my password on my laptop. When I log into my account, sometimes keystrokes don’t register. I physically press the key, but the character doesn’t appear. I noticed that this happens most often when I completely erase my password using the Backspace key. After that, while the system is still loading something, I start typing — and the first letter often doesn’t appear.

Sometimes there are other strange issues: the same letter might not register in a specific part of the password. This happens consistently, and changing the password doesn’t help. If the new password starts with the same letter, the issue still occurs. When I change the password to something completely different, it works fine for a few days, but then the problem comes back.

Does anyone have any ideas on what could be causing this?

[Re-Titled by Moderator]