I’m not using a Google account, so I’ll have to ask …
What are your options in the camera App Settings (cog wheel in the top left corner) - Storage?
Can you set it to “Phone” or “SD card”?
And if set to e.g. “Phone”, does Google still copy the pictures to the Google account?
On second thought, the “Photos” App (managing the gallery) might be involved, but I can’t check, I don’t use that either.
Many users use Open Camera (Play Store / F-Droid).
And I deactivated the Photos App (among others), I use Simple Gallery Pro from F-Droid instead.