I know MySQL has checksums by default, how does it compare? Is it useful or is it similarly weak?

I don't know but LLMs seem to think it uses a 32-bit CRC like e.g. Postgres.

In fairness, 32-bit CRCs were the standard 20+ years ago. That is why all the old software uses them and CPUs have hardware support for computing them. It is a legacy thing that just isn't a great choice in 2025.