Do you fix bugs that appear after a PHP 8.x upgrade?

Yes, PHP 8 turns a lot of old leniency into hard fatals. Common post-upgrade breaks: TypeError from stricter type coercion, deprecation notices becoming errors, removed functions, and named-argument or constructor-property changes in dependencies. We work through the failing paths, patch the code (and bump or replace incompatible packages), and run your test suite green on the target PHP version before signing off.