The Nightmare Course [1], so named because someone with that skillset (developing zero-days) is a nightmare for security, not because the course itself is a nightmare, and Roppers Academy [2] are both good for learning how to reverse engineer software and look for vulnerabilities.
The nightmare course explicitly talks about how to use Ghidra.
1: https://guyinatuxedo.github.io 2: https://www.roppers.org