Yes, changing a type checker tool is not done easily in larger projects, or on the fly, as they all have different edge cases, where they don't infer well enough, or are more lenient than another tool.

I have switched type checker recently in my own Python projects from zuban to ty. ty seems to work better, and is not a one man show/bus factor of 1, though I respect the work that has gone into zuban by its creator. But ty doesn't understand mypy configuration in pyproject.toml ...

I imagine switching a type checker in a bigger project and with more people involved to be a bit of a PITA, until everyone has adjusted their development environment/tooling. Best one can do is research beforehand which tool suits one best, test it, and then stick to it, unless it has unbearable failures.