The deleted building has indeed been removed, but the interim mapping was done mid-construction. Recommend looking at Aug 2024 Esri World Imagery for newest imagery of buildings.

Welcome to OSM! It's great you found an area that needs building additions and started in on it. This particular building could use refinement, though.
Recommendations: 1) use the layers options to look at different imagery to catch the "L" shape of the building, 2) extend the south edge to catch the whole roof and 3) don't forget to "Square" the building using right click or the shortcut key Q.

Hi BaklavaBambino! Welcome to OpenStreetMap! Thanks for adding the extra tags to East High School. One comment is that the node moves you did to match to the imagery provided in the iD editor "unsquared" the building. The imagery isn't always ideal, so I would revert the node moves to what they had been.

Exactly! We're working on a way to make this easier.

Ah! Interpolation lines are new to me, thanks for pointing that out. When I saw this while editing, on a glance it looked like only one footprint had an address. (And apologies for my belated response... I'm sssllllooowwwww)

So yes, each building is a duplex spilt where the indentations of the footprint are. I was there in person, but didn't want to interrupt a BBQ, so I didn't get a close look to see if the units away from the street were A/B or what. 3141 is the north st-side unit, and 3135 is the south st-side...