Some blocks have constant z-fighting with deferred rendering

Steps to Reproduce:

1. Import any resource pack with PBR capabilities;
2. Enable the experimental toggle for Render Dragon features;
3. Switch rendering mode to "Deferred Technical Preview";
4. Place down any of the blocks from the following list:

• Campfire
• Soul Campfire
• Lantern
• Soul Lantern
• Brewing Stand
• Stonecutter

Observed Results:
The flat parts of these blocks' models flicker constantly.

Expected Results:
The flat parts of these blocks are shaded normally, without the lighting clashing with their backsides.

Screenshots/Videos attached: Yes

Notes: This seems to be caused by the light that's hitting one side clashing with the darkness of the backside.