This is a bizarre but effective glitch in many older filters.
While schools have valid reasons for blocking websites, there are legitimate reasons why students may need to access blocked sites. Here are some methods to unblock websites on school Chromebooks: unblock websites for school chromebook
Access blocked websites at school, at work, or anywhere in the world with ExpressVPN, your personal website unblocker app. ExpressVPN This is a bizarre but effective glitch in many older filters