Marathon unplayable, Severe mouse input delay on PC - camera keeps turning when mouse stops

After repeated mouse movements, the camera continues turning for approximately 4 to 5 seconds after I stop moving the mouse. Keyboard movement stops immediately when I release the key. The in-game menu pointer stops immediately but moves jerkily. This happens with both a wired Razer Viper and a Logitech G602. Both work normally outside Marathon, including in other games. Lowering the Logitech report rate from 500 Hz to 125 Hz helped significantly but did not resolve the delay. Current settings are 125 Hz and 500 DPI. Troubleshooting already tried: reinstalled Marathon; tried different USB ports; updated the NVIDIA graphics driver and rebooted; disabled Steam Input and disconnected controllers; disabled Steam and NVIDIA overlays; Discord was not running; closed Razer Cortex; tested different display modes, Low graphics, VSync off, and mouse smoothing off; tested 30 and 60 FPS caps. Delay persists at both; uninstalled Citrix Workspace and rebooted; completed a Windows Security full scan which reported no current threats.

windows 11, 3070 graphics card, 16 g of ram