Resolved _MainTex mixing all the sprites of the same folder

After a lot of losing my mind I found a problem with a parallax shader, for some reason _MainTex is working horribly wrong for a couple of sprites, instead of assign the sprite to the material it is assigning all the sprites of that folder (it took me forever to realise that, everything else seems to be 100% fine)



before running the project:



after, it takes all the sprites of that folder and put them all together:


if I manually assign it instead trusting _MainTex it stays as it should:




if I remove _MainTex and manually assign the sprite everything works 100% fine, why is _MainTex doing this? Those sprites that are being add as _MainTex are not related in any way but for sharing the same folder, simply moving the sprite somewhere else fixes the problem. I never saw this happening before so not sure if it is a bug or me missing something very obvious

 

apparently we have a tool that another developer added that makes a tile map texture even when the sprite looks as a single sprite, not sure why it only affect some sprites but seems to be human mistake