Wow, I wondered if I was alone in this. I thought my sd card was corrupted or something.
I stored almost all my lifetime of phone camera photos in the sd card from 2008 onwards in my sd card, and I also found out a few months ago, photos from 2013 to early 2020 disappeared. My sd card which is usually 90-95% full suddenly became 40% full only.

I also suspected Google photo but, I didn’t use the save space option. If yes how could I only clear a chunk in the middle?

But if it was my sd card damage / corrupt how could TS have 2 of the same problem near the same time?

Do you have other backup apps? I have synology file doing similar thing, backup and a clear but it was rarely working. I also have onedrive. But it was full and hardly working too.