I think it’s because it’s automatically becoming smaller which usually when you change the size of a picture/image it’ll turn more of a low quality. Honestly as long as the testers can see what is being tested, I would say it’s not that big of a deal. But otherwise, yeah it be happening to everyone so idk. Just a guess
it’s purely compression to speed things up - but I’ll pass it for our tech team to look into this and see if it can be improved. On my end on mobile most photos look good including yours (although I can see the difference in high-res you added!)