Im using minecraft 1.16.5, Lithos 32x textures, and OptiFine_1.16.5_HD_U_G8

Are there multiple options for textures that the mod chooses from? Do you think its selecting the wrong variant?

I think it might be it but the only real way to test is find random ass packs or test code/theorys.

We could try changing optifine settings to see what happens

Edit: I know there is a current bug with the mod where if texturepacks change the textures created by the mod become well... random textures... Some examples here cause i cant help but laugh at this. It might be related to this issue because it looks to me like its picking a random texture and doing it. Like the arcadia tree it kinda looks like some weird ass grass xD.

I have the same issues with what seems to be every tree BUT oak. Im doing testing right now to see what the direct cause of it is. So far have not found it with my texture packs. Testing it more. Will attach some pictures after i finish up more testing. I also got a funny one from the side effects of testing xD

Edit one: Im going to try your texture pack. Its something relating to the texture packs cause i turned mine off (Unity) and the issue went away.

Edit two: Finished the little test. Vanilla textures have no issue, the lithos texture pack has the issue with all trees for my client, the unity texturepack has the issue with all trees BUT oak. Screenshots attached.
First 4 are vanilla, Next 4 are Lithos, Next 4 are unity.