Hi,
The tag leisure=horse_riding is not a tag for buildings, but in this changeset you have tagged several buildings with it. This way they are not rendered as buildings on the map. The tag https://wiki.openstreetmap.org/wiki/Tag:leisure=horse_riding is for the whole riding centre (in this case pony club; https://www.openstreetmap.org/node/12296040782 is correct), but the buildings should have a building=* tag instead, e.g. building=stable, building=riding_hall, building=shed, ...; then they will be rendered correctly.

This applies to the following buildings:
https://www.openstreetmap.org/way/363321097
https://www.openstreetmap.org/way/363321176
https://www.openstreetmap.org/way/363321482
https://www.openstreetmap.org/way/363321718
https://www.openstreetmap.org/way/363322299
https://www.openstreetmap.org/way/1329096695
https://www.openstreetmap.org/way/1329096696