I got a Moto Z Phone as a replacement for my defective android phone. After a week, all my older pictures from May 2017 and earlier disappeared. Eventheback ups on Google Pictures disappeared. Now my battery keeps draing in half a day. I email, text, shop less than an hour and it eats the battery. I don't use apps or play games. What gives. Ive optimized and it gets worse. I am more upset at loosing my deceased father's pictures. Our honor flight pictures gone. He died 5 days after the trip.
Look in your trash on Google Photos.
You'd need to reach out to Google to find out why your pictures are getting deleted and see if they can assist in recovering them.