Normally item renaming takes 1 level of xp. However repaircost is influencing it. Also after renaming this tag is updated/created.
Comments 5
The current behaviour is intended, and if you'd like to request to change it, go to https://www.reddit.com/r/minecraftsuggestions/
So even renaming the same item over and over again should increase the cost? Because this is a side effect of this bug. If it is WAI anyway, why this is unconfirmed, and w/ invalid resolution?
This is the case for every interaction with any item in an anvil, changing this would be a feature request, which belongs at reddit.