‎ATT Fiber – North California (Saratoga area) – very latent for online gaming

I switched to AT&T Fiber back in September 2022. My main reason for switching to AT&T Fiber is to be able to play only gaming well (with higher speed and lower latency), especially for my current favorite game, Brawlhalla. I play this game on PS4 connected through Ethernet to BGW-320. I configured the PS4 through Google DNS (Primary: 8.8.8.8 and Secondary: 8.8.4.4), sometimes I also tried: CloudFlare DNS (Primary: 1.1.1.1 and secondary: 1.0.0.1). 

My observation about using AT&T Fiber is:

1. It shows during any internet test that both download and upload speeds are around 600-800 Mbps.

2. During online game time, 99% of the time I encounter latency when I see my character in the game start teleporting uncontrollably and gaming input is sometimes not successfully submitted to the server. If bandwidth is the cause of the high latency, I tried upgrading the speed to 1Gbps and even 2Gbps, and finally, I am back to 500Mbps as I don’t notice the difference in latency.

I feel so upset about this experience that I sometimes consider switching to other providers. Before making the switch, I would like to hear from anyone here if anything I should do to pinpoint the problem and possibly remediate it. Thanks in advance.