That's a maximum/cap, not an average.

Who said it was an average?

I have a similar question: how do I stop Google photos asking me to update every time I open it?

"You're missing out

Update your Google photos app for the newest features"

... I have zero interest in updating. I'm not missing out on anything... other than being able to browse my photos without this annoying message getting in the way.

This is exactly why I don't use it and have it disabled. The arrogance of that message is stunning. I use Aves and it works just fine.

I'm building a photo book system that respects privacy via no tracking, not sending anything to the server until you go to print (all stored in indexeddb until then) and even then requires as few details as possible (eg email address optional), and no sign up at all. Then everything deleted within a month. It's at https://www.rgbloom.com/ and UK only for now.