It happens again also without mod security.
In apache error log I found this:
[Sun Oct 08 01:43:07.337737 2023] [mpm_event:error] [pid 199649:tid 139707479040576] AH03490: scoreboard is full, not at MaxRequestWorkers.In$
[Sun Oct 08 01:43:08.338956 2023] [mpm_event:error] [pid 199649:tid 139707479040576] AH03490: scoreboard is full, not at MaxRequestWorkers.In$
[Sun Oct 08 01:43:09.339942 2023] [mpm_event:error] [pid 199649:tid 139707479040576] AH03490: scoreboard is full, not at MaxRequestWorkers.In$