Are you referring to something on the main page where the thumbnails are displayed? Like how there's a FLAG for 'unwatched'?

I was thinking a small "HD" overlay on a thumbnail, perhaps if HD was included in the title.

Feature request: HD visual flag for HD videos

Topic		Replies	Views
4K Flag added by checkbox Feature Suggestions	2	69	May 9, 2023
Little icon on the poster saying 4K, HD, SD etc Feature Suggestions	2	170	November 12, 2021
Display media info in thumbnails Feature Suggestions	2	135	June 10, 2021
Put a 4K or 2160p tag on the thumbnail in the Grid View Feature Suggestions	3	139	June 10, 2021
Overlay poster for 4k movies Feature Suggestions	5	111	February 15, 2023