Security concern - password keystrokes

I run a macbook pro M1. Normally everything is fine. However, since late 2024, I find that when logging in at my screen saver or entering my password to confirm mac store ,etc. the first character press on my password is "lost". The keystroke has to be repeated. This problem only occurs during password entries for the macbook or appleID. Keyboard testing shows no problems. No problems occur with other logins or applications. Do I have to worry about some malware? How can I find why the first keypress is discarded?