It makes more sense to use base64url encoding as the default, because base64 includes / which will create problems when using it as a filename.
According to the specification table on https://datatracker.ietf.org/doc/html/rfc4648#section-5
base64 encoding contains + and /, which are replaced with - and _ in base64url encoding.
It makes more sense to use
base64urlencoding as the default, becausebase64includes/which will create problems when using it as a filename.According to the specification table on https://datatracker.ietf.org/doc/html/rfc4648#section-5
base64 encoding contains
+and/, which are replaced with-and_in base64url encoding.