This is a fright that turned to fun.
In my morning walk today I travelled along Shanowen Grove, and I took StreetComplete with me, adding building levels, addresses, building types and so on. On the last section of road I discovered one of the buildings to appear on StreetComplete as a tower.
Posting in the #osmIRL Telegram group I shared the screenshot. Dónal came to my rescue It turns out the building was specified to have 21 levels. Looking at the object history on JOSM later it turns out the levels were set by Tshedy see here. However, knowing Tshedy’s level of accuracy and the likelihood that “21” is a typo that was intended to be a “2”. This is very much in keeping with a similar “small”(but big) error in Melbourne.
StreetComplete is a great tool, especially where the basic building objects have been mapped, in a slow stroll along a street one can add serious detail, and the better the initial mapping the easier it is to see which objects require further details.
Comment from CjMalone on 26 October 2020 at 14:13
I made a similar error with StreetComplete, where I inputted the housenumber as the levels. A few weeks later once the map updated I saw my mistake.
It’s great to have different renders that help identify these errors.