The account form here: https://registration.ca.powerschool.com/family/Account/profile uses an invalid email format checker. New top-level domains and valid unicode characters are not allowed, even though they are completely valid. My email is in the format abc@def.family (which is valid) but throwing an error "The email address is not in a valid format."
Interestingly, my account in this community *does* allow these emails.
The format and validation of an email address is actually covered by IETF here: https://datatracker.ietf.org/doc/html/rfc6530 It's surprisingly complex and you should really use a library to do this.