What does Rhino8 break that worked in V7 6 or 5?

What prompted my post, some V8 issues, and now I am seeing more and more V8 users with issues not existing in V7 or 6 or 5.
such as these posts:-
I have yet to start with V8,
I need to just be able to do the basics, but some of these may be obstacles to use. I hope not to me.

if posters also link to their post here, we can see the picture better.