Before I start, I'm really trying to get to like the recent changes Atlassian have made recently, but the struggle is real!
My biggest gripe is that over the last few months, I find I am unable to link cross project epic child work items to parent initiatives (from within the initiatives themselves)
This was a fundamental part of our reporting, and gave us the ability to add a chid work item within the Initiative but alas no more! The only workaround I've been advised is that we add Epics and other work items as issue types into the project (but don't have to use them which sounds like a crazy workaround, given that we have Epics and other work items set in our main hierarchy settings)
I really don't get how there would have been so much feedback from users that would have influenced Atlassian's decision to remove the ability to cross link child/parent work items, it's resulting in our team linking chid issues in many other random ways now.. making much more work on my side to fix it up!