If a minOpTime is specified on the read preference and no server fits that criteria then the tags will be removed from the targeting request: https://github.com/mongodb/mongo/blob/6f7dae919422dcd7f4892c10ff20cdc721ad00e6/src/mongo/client/sdam/server_selector.cpp#L76

minOpTime is optionally enforced, but the tags should be preserved to be possibly used in the switch statement that follows.