The issue is that Samsung Internet (v6.2 & v6.4) uses a fork of chromium, based on v56. Which did not support WebGl2. (So back then all games used WebGL, and worked fine!)
When samsung rolled out their Samsung Internet 7.2, like one month ago, which is a fork of chromium v59, it got official support of WebGl2. So now it returns true on that call. and the issues started.
But WebGL2 works really really bad on mobile. So depending on which graphics people used in their games they got different issue, mostly they just get black screen (they get the color of the background layer actually).
Note, Chromium is now on 67-69 (depending on track), so the Samsung Internet are always using forks of really old chrome versions!
Sidenote: Safari on iOS still has the 'Enable WebGL2' flag default to OFF. So "our" games is still forced down to WebGL on iOS, thats why they works fine still. But when Apple change the WebGL2 flag to On dy default the same issues might happen to iOS platforms as well. And this might happen any time, since apple have the setting experimental atm.
So even if the mobiles can render some stuff in WebGL2 and will enable it, the support is still really bad, so forcing down to WebGL will be a good idea for long time I believe.
(This is just my thoughts and others might have different views on the topic)