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That looks like it might qualify as a newer phone. Based on a quick search, that was released in 2019, while my phone was first released in 2017. So it's probably part of the issue that was mentioned in the thing I read, which means it will hopefully be fixed in the next Ren'Py release. On the downside, this means I can't actively do anything to fix the issue myself, since I'm not familiar with the code Ren'Py uses to make Android files. I may have to figure out a way to re-build the APK version of Demo v5 once the Ren'Py update fixes the issue.

how long would that take aprox

I'm afraid I can't really give an estimate unless I know when the next update for Ren'Py will be stable. I think there may be a prerelease version now, but it's not usually a good idea to release games made with a non-stable version of the engine. I also can't be sure if the fix works until I put out the new build, since I don't have any other devices to test on.

Short version: Depends on when Ren'Py 7.4.3 comes out and whether or not it actually fixes the issue with Samsung displays.