It shows up in the PHP fpm log. The 503 error is random when generated in the browser (not the error log file) and this is when the warnings appears in the attached log when using PHP > 7.3.5. Some Local sites work fine, but at random they will produce the 503 error.
I’ve relayed this to the Local Dev team and learned that we have not compiled PHP 8.1.9 for that version of macOS. It is unlikely that this will be done due to the age of 10.14 and nearly reaching it’s EOL.
We also don’t believe there to be any settings that would assist in reducing the errors since this seems like a compilation issue.
If you have any other questions or concerns regarding this let us know!