I'm using MoreCulling with Vanilla Tweaks Bushy Leaves (download link) resourcepack and blocks behind leaves don't render at all. I can see through walls as shown in the image below.

Info:
Minecraft version: 1.19.3
MoreCulling version: 1.19.3-0.12.2
I have not modified any settings of MoreCulling.
Resourcepack: Vanilla Tweaks Bushy Leaves (download link)

EDIT: I did some testing and seems like this started to happen in version 1.19.3-0.12.0

Should be fixed in latest release v0.12.3
https://github.com/fxmorin/MoreCulling/releases

Thanks for reporting it, I believe this is due to a change in how I handle MultiPart models now.
Before if the model had any part that had transparency (including the small bushy leaves) it would not cull behind it. Although now its smarter and can determine the difference, however leaves are very weird when it comes to culling.

Could you tell me what leave culling options you have selected, what graphics mode you are on, and if you are using sodium?

I was not able to reproduce this using sodium and moreculling (or even just moreculling alone), with any leaves setting. Are you using any shaders?
Can I get a list of mods that you are currently using?

I haven't changed any settings so "Leaves culling" is "default".
My graphics mode is fancy.
I'm not using shaders or sodium (though it'll happen with sodium too).

Mods I was using when I reproduced this:
I'm using Quilt Loader.
Quilted Fabric API 5.0.0-alpha.6+0.69.1-1.19.3
Mod Menu v5.02
More Culling v1.19.3-0.12.2

Oboi Why does it not happen to me than. I don't like that...
Any other resource packs?

I'll check if Quilt is the one doing it

Only Vanilla Tweaks with Bushy Leaves. I'll ask one of my friends to try to reproduce this, I'll update soon on what happens.

Okay, it's happening to my friend also.

I can reproduce this with fabric loader too.

I was able to recreate it, it's when you run MoreCulling without fabric API. I'll attempt to fix it