There is some confusion about Meadows "flipping."

https://abcnews.go.com/US/chief-staff-mark-meadows-granted-immunity-tells-special/story?id=104231281

Immunity is something else: This means essentially that he was forced to testify.

It works like this: If the DOJ gives use immunity, nothing he says can be used against him, so it's no longer possible to invoke the 5th Amendment.

(It's late so I'm not sure I explained it well.)

See:
https://www.law.cornell.edu/constitution-conan/amendment-5/immunity#:~:text=“Transactional”%20immunity%20means%20that%20once,from%20or%20obtained%20because%20of

https://www.justice.gov/archives/jm/criminal-resource-manual-718-derivative-use-immunity