With Paste NG addon active, you can see texts that should be hidden when customization selection dropdown menu is active.
Screenshots below.

What actually happens: First drop-down menu is active but the menu doesn't hide other UI text elements below it

What's expected: Vanilla World of Warcraft UI, the drop-down menu hides other text elements below it

I noticed this on my UI was well and tracked it down to the old Paste addon. While searching it, I found Paste NG and upgraded to the new version, but looks like it inherited this bug which hasn't been fixed yet.

I know the old Paste addon had been abandoned for several years and over the last few years they did a lot of changes around menu backgrounds (it messed up a ton of addons during Shadowlands) so probably something to do with that.

This is caused by the included "LibStrataFix" library. This lib was written for WoW 6.2 and has never been updated since then (2016).

I don't know what exactly LibStrataFix is or was supposed to fix, and it's quite possible that now – 7 years later – it serves no purpose other than causing issues with current WoW.

Try removing the entire LibStrataFix folder (inside the libs folder) and all references to it (in Paste.toc and embeds.xml).

For me, this fixes the cosmetic glitch in the Dragon customization UI without any side effects. But: I don't use PasteNG very intensively, so it's possible that I'm not aware of any special use case that still requires the StrataFix thingy.

If this is the case, we need to take a closer look at the lib and fix it more surgically.

@tflo thanks, I'll try than and see if everything still works

I played around with PasteNG a bit more to see if the absence of the lib caused any anomalies, but I didn't notice any. And I don't think I can do much more with PasteNG than paste stuff into the chat and change settings in the preferences panel, can I?

I saw this issue thread a few months ago, but didn't bother because I rarely visit the drake customizer. But now I'm glad I remembered, because having a 7 year old library loaded, especially a "fix"-type one that hooks into generic stuff that is not specific to an addon, is rarely a good thing ;)

Oh, and I did a recursive search for this library in my active addons folder and my archived addons folder from the last 3 years (that's more than 800 individual addon root folders!), and I didn't find a single occurrence of this library except for Paste.

This makes it even more unlikely that the library is still good for anything.

@tflo I just tested it, and indeed it fixes the issue.
Thank you so much for locating the issue, I know several people have been annoyed by this, so it is greatly appreciated.

Since I removed the lib, I find myself visiting the drake customizer more often. (Nah, it's probably because of my new 50k Pirate's Day saddle, which had to be activated on all toons 🥰)