Inverted Normals in Player, correct in Editor?

I have an object with a Sprite Mesh Renderer in a 2D game. In Editor, everything is lit correctly. When I build the game, the objects are no longer affected by lights and turn dark.

When I flip the object, it’s lit correctly in build and incorrectly in the editor. I thus suspect it has to do with the normals of the mesh.

I have tried some things such as two-pass shaders I found somewhere (quite clueless about how shaders work though, sadly) and also added a Double Geometry Asset Preprocessor, but to no avail.

Why is this happening and how can I prevent it?

it’ll help greatly to add as many screenshots as possible. This is a visual problem, best understood visually. This non-answer may frustrate but I’ve seen questions go unanswered for years so it’s best to give the forum as much info as possible (visually).