Thanks for adding details here.

However, please do not use tags such as "layer=1" on buildings if the purpose is to evade validator warnings.

In this edit, as long as in yesterday’s edit, you created a long footway across a building (https://www.openstreetmap.org/way/1428252282).  This mistake triggered the warning.  Cheating with the layer tags gets rid of the warning but keeps the error.

The correct way to map those situations is to cut the footway when crossing the building and tag the inner part as tunnel=building_passage.

Example of a fix here: https://www.openstreetmap.org/way/1427974749