Per WoRMS: “Maxillopoda is no longer recognised as a valid monophyletic taxon. Its component groups are divided between Oligostraca and Multicrustacea.”
The dividing up of Maxillopoda wouldn’t have been a single taxon change like a swap or a split. Its subtaxa would have been regrafted into Multicrustacea and Oligostraca. Once that had all been done, Maxillopoda would have been empty. The last step would then have been to mark it inactive.
But from what I can see/guess, I think you’re right that that particular message should only be showing on 372744, not also on 47663. Both taxa are correctly inactive, but only 372744 is inactive because of the swap the message is referring to.
I suppose the response might be correct because the URL doesn’t specify that is querying taxon changes where the given taxon was necessarily the input taxon, but the front end should only present the taxon swap as a reason for the taxon being inactive if the taxon is the input taxa of the taxon swap.