Problem with log rotation of roundcube log files

Question

I'm struggling with the log rotation of roundcube log files on my debian 11 server. The amount of files is getting higher and higher, so I have to delete them periodically.

Here you can see, how the files look like. All those suspicious files have ".1" at the end. What can cause this?

I don't want to work around it and delete these files again and again. Any suggestions on how to fix that?

Log rotation config looks like this:

{GUI_ROOT_DIR}/data/logs/roundcube/*
{
   create 640 {USER} {GROUP}
   compress
   delaycompress
   missingok
   notifempty
   rotate 7
   daily
}