The reason you’re seeing a decrease in quality from before you take the picture and after is because Snapchat condenses the file (aka your picture). This is less noticeable on the smaller screen resolution’s which is why it used to work great, however, you have to give Snapchat some time to catch up. However, the issue I am experiencing is the front facing flash completely washing out my face and I look like Edward from Twilight. Probably an issue with the codec or how snap is processing your photos, but it’s extremely bad. Another thing I will mention is that Apple isn’t in charge, nor are they responsible for Snapchat or its bugs. If you want this fixed, you need to post on a Snapchat forum, not Apple’s forums. Apple isn’t going to push out a software update for better compatibility with a 3rd party app. I recommend reddit over this. As far as the grainy pictures go however, that is due to Snapchat compressing your images to make the file size smaller, in the same way that YouTube does it. Think about how big a file size is when you take a picture. Now multiply that by how many pictures you send a day, and then multiply that by how many people use Snapchat altogether. Snapchat can’t handle that from a tech perspective. I would say if you’re not having the flash issue, be grateful, and if you are, submit it to a Snapchat help forum or submit a ticket directly to Snapchat. Also, trust me when I say this, they are probably already aware of it. There has to be someone at Snapchat with an iPhone 11. That person is going to notice the same things your and I are noticing. Not a perfect situation, but just do what you can by posting where it will help :)