I have the HP Spectre x360 - 13-aw0023dx with intel i7 10th gen and Iris Plus graphics. I'm having problems playing 4K HDR @ 60fps on youtube. The video stutters a lot. Here is an example video: https://youtu.be/FrKNa3hruBw. I've attached the stats from youtube FYI
There isn't much problem when playing 4K HDR @30fps like this one https://youtu.be/UPeocNGQPNk
The graphics drivers are up to date (for more information look at the graphics and display report) and the OS is Windows 10 Home Build 18363
Lots of other possibilities before we get to that. Have you downloaded the file and run it locally? If you do and it doesn't exhibit the problem, then it means there's a network bandwidth issue to sort out. Windows 10 2004 has all sorts of folks complaining about bandwidth issues.
HDR works great on my Lenovo Yoga C940 14 UHD with i7-1065G7. This seems like it's a compatibility issue which involves HP, Intel, and Windows 10 as all of them in conjunction must figure out what's going on and why is it happening. on my HP Spectre 15 2020 it's dwm.exe that's causing the issue for me, which leads it to believe it's more of an Intel/Windows thing that needs to get fixed with it's iGPU drivers I'd say.