Nausea

In Minecraft, Nausea is a status effect that warps and wobbles the player's vision, similar to the effect of being in a nether portal. The intensity of Nausea does not change with its level; the vision distortion remains the same regardless of the level. This effect is primarily obtained by eating pufferfish or consuming suspicious stew crafted with a closed eyeblossom. Drinking milk can remove the Nausea effect. In Bedrock Edition and Minecraft Education, when education options are enabled, tonic can also cure nausea. Nausea causes a green overlay to appear on the screen edges, and adjusting the “Distortion Effects” option in the settings can change the amount of green overlay or disable the distortion effect entirely. It's worth noting that only the wither and ender dragon are immune to the Nausea effect; other mobs are unaffected because Nausea is purely a visual effect on the player.