SAML metadata fetch/base64 encoding issue

We observed a strange behavior while setting up a federated EntraID SAML provider. During configuration, the outcome of base64 encoded metadata string differs when using Metadata URLMetadata URL from Metadata XMLMetadata XML. Seems that when using Metadata URLMetadata URL there's an invisible symbol being added 77u/77u/. We did some tests and the SAML IDP configuration with the invisible symbol does not work.