Hi,
these changes look like they are made for a temporary event taking place in the future. OSM should *not* be used for mapping features that exist only for a very short time.

The changes themselves also look wrong, because they create a new building on the basement level. Only features existing in the real world should be mapped.

Please revert these changes and take a moment to study the project rules before continuing.

https://wiki.openstreetmap.org/wiki/Good_practice#Don't_map_temporary_events_and_temporary_features
https://wiki.openstreetmap.org/wiki/Good_practice#Map_what's_on_the_ground