I checked the screen resolution and it came out 812:411. It does not make sense for Galaxy a50, it also does not fit the ratio which is 19.5:9
Screen sizes are in dp.
Screen sizes do not include the buttons at the bottom of the screen.
So for example if a screen is 1080 x 2400 in dp it might be 913 x 411. This includes the buttons at the bottom.
However, Thunkable might show 850 x 411 because it only takes into account the screen available and does not include the bottom buttons.