I have my default photo resolution set to 4k (3840x2160). I have this set both in config.json and in the camera's option menu.
Since 1515 came out, photos I take default to being 1920x1080, even though the in-game camera menu still shows it's set to 4k resolution. Setting the resolution to something else in game and than setting it back to 4k corrects the issue for that session, but it then goes back to outputting 1920x1080 the next time the game is restarted.
Removing the resolution configuration from config.json appears to have no impact on this.