the thumbnails for alerts really help in wading through false positives (bugs flying near camera etc) . The more larger the thumbnail , the easier is would be to assess & ignore these unneeded videos.
I would presume the storage needed to hold a single frame of video of twice the dimensions would be reasonably small, especially compared to the 12 seconds of video itself.
There would be an aditional benefit for Wyze, as users would avoid downloading alert videos which didnt actually interest them, so the load on their system would be lower. thanks