iPhone Mail app shows "Password wrong" for IMAP account

Since today, my iPhone air (IOS 26.3) mail app says "Password wrong" (in German) and asks to re-enter it for the IMAP-Account "xxx" (with xxx being my account's name). It is not a password issue with Googlemail, since my laptop functions normally and I can see/ receive new e-mails. When I enter the correct password, it repeats the error message and the loop does not end. I tried sliding the mail off in settings for mail, but it did not change the situation. Can you help me?