I only found out by accident but when checking the storage on my PS5 I noticed both versions were on it along with two or three PS4 DLC's. Deleting them gave me a nice chunk of valuable hard drive space back.
The PS4 versions of DLC tried to download themselves on to my PS5 too, even though it’s the PS5 version of TSW 3 I’m using. I was able to cancel them before wasting much time.
The only place that I noticed them on mine was under storage in the settings, on the PS5 where you, or at least I do, go to delete things to make room.
When I chose to add some of the TSW compatible routes this morning I did notice in the downloads that there was both TSW3 PS5 and TSW3 PS4 listed. I just selected the TSW3 PS4 download and cancelled them all.
I downloaded some routes and it started downloading for TSW2 as well (routes I don’t have on TSW2 currently for DLC cap reasons). I was cancelling downloads left right and centre. It was like whackamole. PS4 version - whack, TSW2 version - whack, repeat.