Found out this makes the arrow invisible to the player who shot it.
[media]I could've fired it from a normal crossbow and edited the function for arrows shot from any crossbow but thought it wouldn't be a problem and I also forgot to open the F3 menu. Should've done that from the start to clear up the ambiguity.
This is not a modded client. Those are items witch custom model data and a resource pack. The arrow was shot with a vanilla crossbow with a different model and texture. The lead that appeared was just from a datapack function and has nothing to do with the bug report.
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Thank you @unknown for the workaround. Sorry for the duplicate.
I managed to get an item name in chat from a give command to display blank in 1.16.2
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