The first Apple Watch Series 7 units are already shipped and there appears to be an issue right out of the box. According to some users, third-party apps don't appear with their icons and instead, they are invisible on the home screen.
It was first spotted by a developer working on products related to Apple's ecosystem. He clarifies that the simulator in Xcode displays the icons just fine but they don't appear on the actual watch. Some believe that this is due to the new screen dimensions and resolution because the icons are perfectly fine on older watches, even when running watchOS 8.
A temporary workaround is to switch the home screen's view to "List". Keep in mind that the icons would still be missing but at least you'd know which app is which as the list view displays the names as well.
After updating to 15.0.2 I experience so many bugs that I started to regret chaning my phone from Samsung to Apple.
It could be a new subscription based thing, where app developers pay Apple to have their icons show on the Apple watch. No pay, no show... :D