@Palgrave Peter: The recommended way is to hit the upload button in StreetComplete *before* moving on to another territory.

It looks like you had solved some quests in Cyprus, which you hadn’t uploaded, and then you used StreetComplete again in London… uploading past and current changes at the same time.  That explains why your changes create a huge bounding box that spans across most of Europe.  This is an annoyance for thousands of mappers.

Hope this helps.