The PS4 version must use it's own in-game region based server for better latency just like every multiplayer game not the PSN default. I'm currently getting 250ms in every session just because
Genshin Impact: a notice of closure to be feared on PS4 and PS5? - Millenium
How to enable cross save for Genshin Impact on PS4 & PS5
Genshin Impact
How to redeem Genshin Impact codes on Mobile, PC, PS4, and PS5
Genshin Impact [News]
Genshin Impact FAQ - Play with friends, Update Failed, Slow Download | VG247
Genshin Impact Coming to PS5 'Soon' With Enhancements - IGN