All of these things are less serious problems if things move faster. QA review of the master branch is the only thing you’re doing that has to be long running and synchronous.

For your acknowledged problems:

1. This is huge, and should be a focus for you.
2. This isn’t actually a big deal. Outside of fixing bad prod deploys, reversion causes more problems than it solves. If you get the devs out of QA, the need for this will decrease.
3. If you freeze the code on tuesday and release on thursday, that sounds like a schedule!

It sounds like the QA department is overwhelmed. You need more test automation in order get the turnaround for regression testing down. Many end to end test tools have recording functions - a senior QA or engineer in test could quickly get simple but brittle automation in place.

Devs need to understand that QA stopping the line is a last resort, not a personal safety net. More unit and integration testing will keep more of the work on the devs until it actually is ready.

What does your source control and CICD situation look like?