Youtube screen time bypass using google embedded youtube previews.

There is not. Blocking is done by the website name and there are many places on the internet that just provide "portals" to other content that makes blocking by website useless for those looking to intentionally bypass your rules. In some cases, the best course of action is still to take a device away until they are able to be trusted with the responsibility of a smart phone. There are also "dumb" devices still sold that don't provide internet access at all and only have phone service for about $30. In some cases, a child would much rather follow rules, then be caught with one of those phone.

Another tactic kids use is to FaceTime a friend and have them share their screen to run apps on that phone so it is not counted on any of their App Limits. Screen Time just gives you some tools, it is not a replacement for monitoring a child's activities, and there still needs to be consequences for bad behavior.