Here are the most common mobile screen aspect ratios in 2019:

• 16:9 (1.78) 69.12%
• 18.5:9 (2.06) 8.96%
• 19.5:9 (2.17) 4.56%
• 2:1 (2.0) 3.10%

This means, if your game is 10 blocks wide, 86% of users will fit at least 18 blocks high, and max 22 blocks. Presumably some of the other 14% are on tablets with a 4:3 (1.33) aspect ratio, only seeing 13 blocks high.