In at least as of v2025.06.01.2212, you can see that Manage Art is available under DVR -> Manage:
However, within a Movie, Show, or Video Group, it is MIA:
I have noticed this in at least the past couple of prerelease versions, too, but thought it was item specific. Now, I recognize that it is happening everywhere with everything at the top level. Bottom level episodes and videos do still have the options, though:
EDIT: And as soon as I posted this, I noticed that there are now little icons on the images:
These give that old functionality. I would still prefer to also have the menu options as it was much clearer to me and I wasn't aware these were being removed and moved solely to icons.