WWW tag being automatically converted to "user defined URL link"

Is there any way to circumvent this? My music player does not currently recognise the tag mp3tag stores WWW as, is there any way that I can stop it from saving as "user defined URL link" and instead save as "WWW" like it is specified in the tag panel.

With a program like mp3diags you can check which tag MP3tag uses to store data.
WWW is saved as WXXX (as you can also see in https://docs.mp3tag.de/mapping) which is according to standard.
A user defined field would start with TXXX.
So to circumvent the problem, the only way I can think of: use a different player.