You used older imagery to add these buildings. The situation has changed drastically since the images you see in bing; entire settlements are present in some imageries but not others. 

Alternate imageries can be useful, but you should check and be confdent that the features you're adding are present in the most recent imagery. Start by refering to the project instructions when choosing what imagery to reference. If you later find that you have made a mistake try to fix it, or state it in the comments section of tasks; it's helpful for others contributing to the project.
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            Published using OSMCha: https://osmcha.org/changesets/152850117
            