Well then maybe consider making a sql replication client that would ingest the changes (like most databases, mysql writes to a straming append-only log, before it is compacted). Just parse the log and act on them.

Not trivial, really? Here, enjoy: https://github.com/krowinski/php-mysql-replication

That means they did implement change data capture, and only exposed it for a very specific use case.

Well, good. Your problem is artificial, choosing tools and scenarios to avoid "push". Your problem isn't with invalidating caches being hard in 2025. I've explained how to do it in both pull and push scenarios. Certainly not "the only hard problems in computer science." And neither is naming!

You didn't implement change data capture. You're using theirs.

I’m also not making my own programming language, I’m using PHP. And I’m using MySQL. What is your point?

Are you saying that “invalidating caches is hard… if you insist on using only systems with no way to push updates, and oh if they have a way to push updates then you’re using someone’s library to consume updates so it doesn’t count?”