Out of the box it can play audio in the background, and now that extensions are available you can block ads as well. You don’t really need constantly updating 3rd party clients or questionable firewalls anymore if you just want usable youtube on a phone.
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It seems it may be because Orion on iOS has web extensions support. Which I think safari also does (partially) but uses a different framework for its on extensions. Check out Kagi’s page on Orion and web extensions.