If your ISP has IPv6 enabled, look into disabling at your router and/or device and test it out (its easy enough to reverse with no damage/risk if things don’t get better). At least for me (Comcast) recently rolled out IPv6 in my area and disabling it instantly resolved all my issues.
My old issue thread: Rubberbanding/Lag Issue Replication & Detailed Steps
My workaround/solution: [Solution/Workaround] Rubberbanding/Latency Spikes / Comcast