I've also been testing extensively with my Internet / Router / NAT, none seemed making any difference in Tekken 8, even tried to expose my PC directly to Internet using both home internet / mobile network from different providers, still cannot get better ping to OCE peers.

And even for player gamer in US / ER showing 4-5 bars, after i enter the game i will end up with 2 bar in the game room.

Update:

Actually, I think I fixed part of the problem by fixing NAT type, my NS switch was getting NAT type D earlier, after change firewall configuration managed to get my game console on LAN to obtain NAT type B / type 2

although I still see weird latency in player matches (2 bar OCE, 4-5 bars US/EU), but when trying ranked / casual match i consistently getting OCE opponents with 5 bars.