A few updates back (maybe 5-6 versions ago) I did Clear All Metadata to re-download them again. I guess that was not okay because now some of the TV Shows Cover does not show (Example)
Version 7.1.3 (7.1.3830) on (iOS, iPadOS, macOS and Apple TV 4K)
You can see the screen cap on my original post, as for the file naming all of them I followed the guide on Metadata 101 post with seasons on separate folder for every show.
as you can see some of the old shows and all the new shows I add have covers but some of them do not, they did before I cleared the metadata in general
The reason I asked to see how you had the files named and the folders that contain them are named is that from looking at your two examples it appears that all of the show with years in the name are not showing the artwork and the ones with artwork do not have the year.
Seeing how you have the files named and the folders named may help.