The "shard monitor" cursor that each change stream opens on the config server replica set uses the read concern of the change stream:
https://github.com/mongodb/mongo/blob/493e0058075cb8ac67d1eda1cea94417ab11d30c/src/mongo/db/pipeline/sharded_agg_helpers.cpp#L116-L119

A majority read concern may be more appropriate, however, to ensure that the change stream never observes topology events that get rolled back.