One major difference between uBOL and AdGuard is that AdGuard is using the native content blockers function in Safari in addition to an extension, while uBOL is only an extension.
This is major because extensions on iOS do not run in PWAs or web previews but content blockers do (on MacOS extensions do run in PWAs).
So if only using uBOL on iOS, there are no content blocking capabilities in PWAs. This would go against the usual recommendation to use PWAs over native apps for privacy.