This is either a GPS error or a mapping error. You should report it (try “bug-report” voice command, then create a service ticket in the Tesla app and mention your created bug reports) and/or you should check “open street maps” website (openstreetmap.org) for the speed limit and road data for the sections that are consistently showing that incorrect behavior. Submit change requests.
byg report won't do anything
service center won't fix it
also openstreetmap has the right speed limits for ages but it's still wrong here .