Since this topic keeps coming up in other threads I'll chime in with my $0.01 here. We've been using CentOS 7 for awhile (and working on migrating off) but have had to leverage devtoolset/llvmtoolset for various reasons. I remember a discussion of installing a different compiler coming up but don't remember which thread that was in/what the outcome was. While I'd like to just brush over C7 and say there is a compatible compiler available so just make the change I also realize that making that change could be quite disruptive to existing code bases.
However, the 22.11 LTS will be EOL in Nov 2024. CentOS 7 is EOL Jun 2024. For the 23.x series and going forward I don't think starting with a C11 requirement is an unreasonable ask.