Apple’s TVOS has zero ads and is very simple, but it’s also Apple.
My other choice would be a good Android TV box on an NVIDIA Shield or something since you can use third party youtube launchers and third party apps. I haven’t personally used it though so YMMV.
PC prices are crazy right now, but if you can find a used Lenovo ThinkCentre, I’d go for that.
I’m running an m720q and it’s neat because you can get a riser board and install an extra PCIe NIC of your choosing.
If you don’t want to go that route try to find a mini PC with 2 intel NICs, since they’re historically the most reliable and well supported.
Depending on the firestick you may be able to jailbreak it.
A towel!
Probably your lemmy instance censoring a word contained within what was written.
What hardware are you running?
Not sure about settings but I just tried on my Pixel 6 Pro and it wasn’t slow.