Fc gameplay issue for years on my main account

I am experiencing very poor gameplay responsiveness on my PS5, but only on one specific account. My other account plays perfectly fine under the exact same conditions.

I have already deleted local personal settings, rebuilt the console's database, and cleared the system software cache, but the issue persists. Additionally, my network is prioritized via QoS with no other devices connected. Could there be an account-specific profile sync or routing error causing this?