Problem is Redguard sustain is way better than any other stamina race + ofc th highest max stamina passive and with sustain being a major issue in PvE Redguards have become almost a must if you want to reliable play. Also when ZoS balances stamina sustain Redguards oversustain so they have to tone it down making it harder on the other races.
Stamina races are pretty cool and has a lot of options like Woodelf, Khajiht, Orc, Nord, Imperial but without the sustain endgame players just go to Redguard.
The solution is to either make sustain not an issue for other races and let Redguard over sustain or to nerf Redguard sustain and adjust overall sustain accordingly.