As part of BUILD-13242 we have migrated pgp keys to a new web address: https://pgp.mongodb.com/<key name>. While the old address (mongodb.org/static/pgp) will continue to work via redirect to the new location, we should begin encouraging users to use pgp.mongodb.com directly so that one day we can drop support for mongodb.org/static/pgp. There are a few places where I can see this endpoint was referenced, e.g. https://www.mongodb.com/docs/v5.0/tutorial/install-mongodb-on-ubuntu/. There are probably more references I haven't found. Each of these should be updated to reference pgp.mongodb.com.
Let me know if you have any questions!