There is a redesign of the data-block selectors in master now.
Initially this was needed to allow library override operations there, but a number of other design changes were done as well.
Basic idea is to add a menu next to the name-button, giving access to a list of operations. The list is supposed to be rather consistent, so that buttons don’t just disappear all the time. In addition to that, some of the buttons that were previously next to the name field are now either inside the menu only, or available as icons within the name field.
For the last bit, improvements for superimposed icons were done too (tooltips & highlighting support).
Refer to the release notes for more details.
This thread is for gathering feedback on the changes, to help polishing things before 2.92 release.