We are running different Apache 2.4 installations on Debian Servers from v8 to 11, also with different Versions Certbot.
This issue is present on all machines. Regardless the configuration.
Forgot to mention that i already tried to create new certificates with --preferred-chain "ISRG Root X1" also.
And like i said, if switching to a cert from digicert, without changing any other configurations, the problem is gone.