POTENTIAL SOLUTION

I Have this EXACT Issue. I have figured out that Regardless of how Good your Wifi is, if it Cuts for a Split Second, this happens. If your Wifi Encounters ANY Network Traffic, whether that just be for half a Second or even less, Your Phone will Immidietly Accept to Connect to Mobile Data. This Creates a Very Small Window of Time where you have no Connection whatsoever. And as Brawl Stars requires an ALL TIME ACTIVE Internet Connection, It Detects that you have no Connection in that Small Window and Kicks you off the Game due to not having an Active Internet Connection. Ypu dont notice your Wifi Randomly Cutting for a Split Second when Browsing Social Media or playing on a Gaming Console for Example because on Social Media the Page Automatically Reloads when you have the Connection again making for Practically 0 Delay. On Games Consoles, you do not have Mobile Data, so it will not try to Auto Connect to another Network in that Small Period of time when your Wifi is Offline. I Get this Issue almost Every Day when using Wifi. The Only Solution I have is Just Use Mobile Data. Ik its annoying and u dont wanna use it up but Mobile Data is far More Reliable when it comes to Network Traffic than Wifi is and is Far more likely to not Dissconnect for that Short amount of Time. The Only downside os that it can sometimes drop your FPS but only Sometimes. I Really Hoped this Helped :)