A number of iPhone users are seeing a strange green tint on their devices’ displays for a few seconds after unlocking, and it’s still unclear what’s causing the phenomenon. Based on the complaints posted on Reddit and the MacRumors forum, the most affected devices are the ‌iPhone 11‌, 11 Pro and 11 Pro Max. However, some iPhone X and XS users seem to be experiencing the issue, as well.

Several users are saying that the green tint only shows up when they have Dark Mode and Night Shift on or if they’re in dark room. Affected users are also reporting that the issue popped up after iOS 13.4 came out, though there are those who’ve only noticed it after upgrading to iOS 13.5. At least one user says the green tint disappeared upon installing iOS 13.5.5, which is currently in beta, so it’s looking more likely that it’s a software issue. We’ve reached out to Apple for a statement and will update you when we hear back — if it is a software issue, then the tech giant is bound to roll out an update that’ll fix it in the future.