Any dropdown where you can choose data-blocks currently shows single letters for some data-block states, such as "F" for fake user, "L" for linked, etc.
The function responsible for that is BKE_id_full_name_ui_prefix_get, and it only seems to be used in this one context.
As the UI has been updated to use icons instead of these letters for the most part, it feels like this user control should be updated to fit in.
I've provided a screenshot of how it could look like once updated. It's a simple code change in theory, but I don't think I can fully implement it by myself (because of handling multiple prefixes, different DPI settings, ...).