This problem: "Some results have been removed because Restricted Mode is enabled by your network administrator." and "This video is restricted. Try signing in with a G Suite account."
I am using ubuntu 18.04.4 lts. I encounter this error on youtube in all browsers. I'm sure the restricted mode is off but sometimes it happens sometimes not, so it doesn't always happen, but I couldn't understand what it's about. Besides, the error continues whether or not I am logged in. I cannot view many videos on youtube without using vpn. Windows is also installed on my computer, there is no such problem. ***I'm deleting this question a third time and asking again, is there really anyone to help?
Just had the same issue after nuking my computer and rebooting it with Ubuntu 20.10 and Windows 10. What I had to do was log into my internet service provider's website (Xfinity) and reassign the device from the default profile, which had parental controls enabled, to my own, which had them turned off. I know you said you didn't have issues with windows on the same machine, but it's worth a shot if you haven't tried it.