Yeah, only works if all used Actions would use SHAs too, which is not the case.

Positive example: https://github.com/codecov/codecov-action/blob/96b38e9e60ee6... Negative example: https://github.com/armbian/build/blob/54808ecff253fb71615161...

I've also found many Actions that do other dodgy stuff, like pulling and executing unpinned scripts from external websites, or installing unpinned binaries from GitHub releases. Pinning an Action isn't enough, you have to audit it.