The issue has been highlighted on Reddit and Twitter after Instagram users updated to the latest version (75.0), which was pushed to the App Store on Wednesday.
The resulting effect is that the Instagram interface looks as if it's been zoomed in, leading users to complain about blown out images, fuzzy text, abnormal spacing of icons and other graphical elements.
The issue isn't turning up for iPhone XS users who have updated the app, presumably because it shares the same resolution as the 2017 iPhone X. Instagram added support for the new iPhone XR and XS Max screen resolutions in October.
Now I know for sure it's not just me:@Instagram for iOS just un-optmized for iPhone XS Max (and presumably XR) screen resolutions in their latest (75.0) update.— Will Sigmon (@WSig) December 18, 2018
Compared below are my wife's XS Max running 74.0 & my XS Max running 75.0. Notice the story bubble spacing up top: pic.twitter.com/ePqKbYnvUL
This is almost certainly an accident on Instagram's part, so it's likely to be fixed in the next update. iPhone XR and XS Max users who are experiencing the issue are advised to hold tight, and anyone who hasn't updated to v75.0 should probably wait until the next version is released.
We've reached out to Instagram to find out when that might be and will update this article if we learn more.