Alpha channel in textures

More experienced texturers know what an alpha channel is: it is responsible for the transparency of the texture.

I just ran into this problem. The game doesn't want to make the texture translucent. Alpha ranges from 0 (completely transparent) to 255 (solid). If I set the number above 127 (half), the color will become solid, and if below 128, it will be completely transparent, but not translucent in any way. In the Blockbench program, it is displayed normally: a translucent texture, but in the game there is a huge weirdness. Can someone know the solution to this problem? Can some plugin help?

I create textures in the program: Paint.net