There are more than 2.5 billion active Android devices so that 50M+ number is pretty insignificant (<0.02%). For an idea of the numbers involved when dealing with Android downloads Microsoft Word has a 1B+ badge, Facebook has a 5B+ badge and there is a 10B+ badge on Gmail.
I have downloaded several iOS style launchers over the years, often just out of curiosity or to prank someone, none of them have stayed installed for more than an hour and definitely never more than a day or two. Even when installed they were not the default launcher. I've used launchers that imitate Windows Phone and other OSs over the years, some for years, others for as little as a few minutes. Part of the fun of Android is you can do this and you are not stuck with your decision.
I've done the same with iOS devices. I've used several apps that simulate being launchers that gave the look and feel of Windows Phone or Android to prank coworkers into thinking I had switched the OS on the iPhone. Unfortunately since they were not true launchers, due to Apple's restrictions, they could do a convincing job of running a handful of simulated native apps (Solitaire, Notepad, that sort of thing) but whenever an actual iOS app was launched from it the "launcher" would have to be relaunched after that app was closed.
FWIW: I did a quick search for launchers in the Android Play Store and found that currently with that search...
Nova Launcher, Microsoft Launcher, Launcher iOS 16, Phone 13 Laucher iOS 15 all have the 50M+ download badge.
Poco Launcher, XOS, HiOS, APUS Launcher: Theme Launcher, Solo Launcher-Clean,Smooth,DIY all have the 100M+ download badge.
So this is not the first iOS knock off launcher to reach this number and this number is not even in the top tier of third party launchers.