I dont know what happened but it doesnt look good

https://www.curseforge.com/minecraft/mc-mods/litematica

NOTE: If you have Optifine installed, then there are some options that you most likely will need to disable in Optifine, or otherwise it will break the schematic rendering:

• Render Regions needs to be disabled
• Shaders need to be set to OFF, or alternatively disable VBOs in the vanilla Video settings, and disable both the 'schematicOverlayModelOutline' and 'schematicOverlayModelSides' options in the Visuals category
• Fast Render might also need to be disabled if there are still some weird HUD/GUI rendering issues

Have you already read and tried that?

Not sure if this works for 1.14.x but in 1.15.2 apparently if you use shaders, you can load up the game with shaders and still use them

Yep this is caused by the changed vertex format when using shaders. I can potentially (partially?) fix this though.