Xiaomi / Redmi / Poco
Xiaomi/Redmi devices usually work just fine with Smart Launcher. If you are experiencing some issues, here you may find the solution you are looking for.
As the message clearly says, this is not a problem caused by Smart Launcher, Xiaomi doesn't allow gestures to be used with third-party launchers since Android 11. The problem cannot be fixed by the SL devs but it can only be fixed by a future Xiaomi update.
This is a known bug. Unfortunately, we cannot fix it, because it is caused by another app (MIUI clock app) which communicates erroneous info to Smart Launcher.
This behavior is consequence of a change in MIUI 11 and it's totally independent from Smart Launcher. Now you need to enable the option Display pop-up windows while running in the background (in Settings > Apps > Rights > Other permissions) for each widget you want to use on your home screen.
You can read more details on the Xiaomi official community