Apache's "built-in" OCSP stapling implementation was historically total garbage and unsafe to use. If you are using mod_md then that's safe, because it was written by somebody who understood what they were doing, 2.4.46 should have mod_md but I can't tell from what you've posted that you're using it and I suspect not.
You are of course free to keep using the built-in OCSP stapling but stuff like this will just sometimes happen, and since there's a decent implementation now (in mod_md) it hardly seems worth yelling at the Apache developers for doing a bad job at this point.
Oh, and yes I checked your site was actually broken, this has nothing to do with Firefox other than that Firefox actually implements OCSP Must Staple and so it rejects the broken site unless you explicitly configure it to carry on unsafely regardless.