I used this feature for the longest time back when Photos storage didn’t count towards your free 15 GB if you used the compressed option. And then they went and made it so everything count towards your 15 GB no matter what quality you were backing up at and suddenly my account was using too much storage space to keep receiving email. I go into Google Photos to clear out some of the largest pictures and videos to get a few gigabytes back, and it tells me that if I do that it’s going to also delete those photos stored locally on my phone. So now Google Photos is uninstalled because if I ever let it back on my phone it’s going to delete all my pictures.