I noticed a new user adding maxspeed=US:urban. I've lived in many cities across the US, and have never seen a consistent maxspeed for anything, from residential to motorways (Interstate highways)

Can that feature be turned off for countries without established speed limits?

The changeset, https://openstreetmap.org/changeset/55834170 was by a new users that has probably never seen how streets are tagged.