"Modern" Libraries Should Respect "List Experience" Setting
The List experience setting in List Settings / Advanced Settings seems to generally be ignored. I suspect that the user preference from one library is set with a cookie and that choice then applies to some other libraries, even across tenants.
If you'd like us to use the "modern" library pages, we need a reliable way to turn them on and off - whether for all users or just for ourselves.
This inconsistent behavior makes it extremely hard to debug issues, not to mention explain the value of the "modern" libraries in the first place.
Star D. commented
Out of votes, but supporting this idea