Wow thank you so much! I'm really happy to read this and glad that you liked the game!
I created a shader using the shader graph of the Unity to create the effect in the hearts and everything else. This shader allows me to take a texture and make something like a sprite mask, but a sprite mask that can be animated and more efficient (I guess, because the tests I've made before using sprite mask for this effect was a real mess) .
And thank you again for the compliments! It's really nice to see when someone likes our games!