Cursor Lag / Stutter & Media Blacked Out Wondering if anyone has a solution to the HDCP issues with external monitors. I'm fairly desperate for a solution.
I have a 2019 MBP 16, and I’m having cursor lag/stuttering, and media is blacked out on my new LG 4K monitor. Seems to be very, very common and yet I haven't found a solution anywhere.
Things I’ve tried:

Reset smc and pram.
All different cables (currently using usb-c to DP).
All different resolutions and refresh rates.
The “detect displays” trick.
Safe mode (no problem in safe mode).
Toggling the auto graphics switching.
Disconnecting all other usb peripherals, and tried every port.
Resetting everything on the monitor.
Downloaded LG's OnScreen Control, and Screen Manager; neither has any firmware update available or solution

Weird things:

Worked fine for about 2 hours after first hook up.
Works fine for about 1 minute after turning the monitor off and on.
Older monitors work great.

I’m working on a graduation project from a programming boot camp, so reinstalling OS or upgrading to Big Sur is a little too risky right now, plus I’ve read it actually gets worse with Big Sur.
I spend 12hrs a day working on this laptop, so if anyone has any input, I would be very grateful. It sounds like a common problem, and I find it hard to believe people are living with the mouse lag day to day.
Thank you!
How is the monitor connected to the machine, USB-C or HDMI? I and others are having an issue with cursor hangs with USB-C connections, sometimes to monitors sometimes to hubs. I would try using an HDMI cable, or honestly vice-versa, and seeing if that helps.