Extracting sprites from sprite sheet has issues- blurry/ pixelated/ broken? VT Texture?

Based on your screenshot, your sprite sheet appears to have a lot of Mips, which I believe work something like LODs. Below are my settings, you might try to duplicate them and/or look into Mips.

Mips in Unreal Engine 4 (UE4)/UE5 - Create Custom Texture Groups — Chris McCole