I see Loader issue with inline tag editing but here I am not reporting an issue; I am asking what it's called and what it's for
When I edit the tags on a question using the tag editor, sometimes I see a display of large gray bands scrolling from right to left. Once the edit is accepted they disappear.
Question: What is the purpose and name of these big gray bands moving left to right when I try to save a tags edit?
Details if relevant: It's generally on my old laptop: macOS 10.11.6 and Chrome version 91.0.... (incognito mode)