Device: iPhone XS Max
OS: iOS 12.3.1
Game Version: 22.1.0 Build 600
After updating, all hero images load with an extremely low resolution image initially. Following a noticeable delay, the high resolution image is rendered. The high resolution images appear to remain cached. The delay is more prominent when on wireless data. On WiFi (1 Gigabit download) the delay is less noticeable and the image typically renders in high resolution ~50% of the way through its expand animation.
I am not certain if this has always been the behavior, but it’s impactful enough to user experience that I think it warrants a post. This may be a sign of uncompressed images being deployed as part of the the release.