The service road for the school is tagged as access=private, which indicates that the object is not to be used by the general public. Access is only with permission on an individual basis. This would be the usual case for a gated road on school grounds, unless there was a public right of way.

Adding motor_vehicle=yes + bicycle=yes + foot=yes implies that the public has an official, legally-enshrined right of access using those transport modes; i.e., it's a right of way. Please could you confirm whether there is a public right of way, or revert your change?

Thanks.

There is a full explanation of tagging in OpenStreetMap here:
https://wiki.openstreetmap.org/wiki/Key:access