When starting the game, the log prints messages like this:

[01:24:24] [Worker-Main-6/WARN] (Minecraft) Texture terrariamod:particle/leaf with size 10x10 limits mip level from 4 to 1
[01:24:24] [Worker-Main-6/WARN] (Minecraft) minecraft:textures/atlas/blocks.png: dropping miplevel from 4 to 1, because of minimum power of two: 2

When Minecraft is assembling its texture atlases (block textures, item textures, etc), it wants every texture to be at least 16px wide and have a resolution that is a power of 2 in each direction (16px, 32px, 64px, and so on). If it encounters a texture with a different size, it cannot build mipmaps for the texture atlas, meaning that the "mipmaps" option in video settings has no effect. Even 1 incorrectly-sized texture is enough to break mipmaps for everyone. This is unfortunate!

I've noticed particle/leaf (10x10 across 5 frames), block/trees/giant_glowing_mushroom_stem (16x8), and block/wooden_beam (14x14) having this issue, but there may be more textures.