Pins that I have not set up appear and sometimes disappear on the minimap.
I think this is, I think, a pin I created with the save data of a previously deleted world with the same name.
Is there a garbage file left behind?

Map atlases : 1.20-2.7.13 / Moonlight : 1.20-2.8.8.84

Yes save data is stored in a folder with same name as the world. In your case it would indeed keep them. I need to delete them when you delete a world

No good. The ghost pin has no tabs, so in-game delete operation is not possible.

So I have to delete the file (nbt) in order to get clear of the pin ghosts?
I have a lot of pins that I have officially set up in my new world, and I don't want to delete them...

yeah. they shouldnt be ghost pins though so you could also just delete them manually ingame

thats weird. so they show on maps but are not on a tab? can you send me your pins file? Should probably make that save in json instead, nbt is harder to read

Data will now be erased upon clicking dele world