Dieter Bohn, The Verge:

After five years of offering unlimited free photo backups at “high quality,” Google Photos will start charging for storage once more than 15 gigs on the account have been used. The change will happen on June 1st, 2021, and it comes with other Google Drive policy changes like counting Google Workspace documents and spreadsheets against the same cap. Google is also introducing a new policy of deleting data from inactive accounts that haven’t been logged in to for at least two years.

And:

Google already counts “original quality” photo uploads against a storage cap in Google Photos. However, taking away unlimited backup for “high quality” photos and video (which are automatically compressed for more efficient storage) also takes away one of the service’s biggest selling points. It was the photo service where you just didn’t have to worry about how much storage you had.

This is certainly a major change to Google’s longstanding policy, but it does give you plenty of time to move your photos to other options if you don’t want to pony up for a monthly payment.

Apple only offers 5GB free before you start paying. Though Apple’s policy has never gone from offering free storage to charging you for same.