Are these all for the same account, or one for each unique account? Please clarify the issue. Thank you.

Good afternoon, in each account, create several inboxes, inbox1-2-3... at the moment we have 7 email accounts and 3 of them are like this. Thanks for the help

If you are experiencing multiple inboxes for the same account, that indicates that thunderbird is having problems saving the folder after retrieving messages. That may be happening due to an antivirus or firewall program interfering with thunderbird.

Good afternoon, The antivirus we use is Microsoft Defender, which comes with the system, can you tell me if there is any way to avoid this situation. Thanks

I have no idea, as I don't know all software running on your PC, and I am not a guru on all of that. All I know is that what you described are symptoms of interference with thunderbird. another possibility if the message folders are huge might be that their size itself is causing difficulty in writing to disk.