In most other browsers I've used, disabling hardware acceleration is something users are able to do. If I recall correctly, this used to be a feature on Safari too but it's been removed. Browsers are definitely not my area of knowledge so I don't know if this has anything to do with WebKit or not but, as a user there are some use cases I have for disabling hardware acceleration. Thanks for looking into this! 
3
Disabling Hardware Acceleration
Hi Vlad, sorry to be a bother but I looked in this submenu but I was not able to figure out which experimental features turn off hardware acceleration. If you have any ideas, please let me know. Thank you
2 years later
Im finding it difficult to disable graphic acceleration. Sure these may be vague terms, but I am unaware of the details.
I believe OP, and myself, are looking to disable graphic acceleration.
Use case:
When streaming in discord, for example, the video playback is black and people cannot see video playback on my stream. When disabling 'graphic acceleration' or 'hardware acceleration' in other browsers, video playback becomes viewable during stream/screen share.
Orions experimental features section is confusing to me as I dont know what I am looking for in all those options in all honesty.
The image below is the setting from edge allowing to disable graphic acceleration. This is what fixes my issue whenever I share my screen or browser on discord.
No one is typing