@Adarnof I’m running an Ubuntu VM (from within ESXi), with passthrough for the GPU. For a lot of my recent testing I’ve had a snapshot running the latest experimental PMS plus latest 525 Nvidia Drivers. Today though, I’m just running my “normal snapshot” that is PMS 1.29 and 515 drivers 
What happens if you leave “Use hardware acceleration when available” checked, but turn off “Use hardware-accelerated video encoding”?
I nearly didn’t try this (your question above), thinking “that’s not going to do anything!”… But, erm, it actually seems to fix the problem with the browser??? How did you get on with testing this yourself?.. For me, I can switch between bandwidth mbps (from Chrome/browser) and though it’s slow to pickup again it seems to just work🤷♂️ I’ve tried on a couple of 4k files and a 1080p file and haven’t had one repeat of the issue? The only thing I saw, once, was it switched to none NVENC transcoding, but it was just the once and I can’t get it to repeat.
I took this screen shot just to show HW transcoding was working 
I did have tone mapping off for this, so I’m just going to try again with it turned on. Though, to be fair, I had no colour issues with it off? And used 2 x 4k HDR files 
Which I think is quite odd?!
