DIAGNOSIS: The camera's infrared (IR) LEDs are reflecting off a surface directly in front of the lens, causing "IR washout." This often happens if the camera is placed inside a window looking out or facing a glossy surface.
FIX: You need to eliminate the reflection. 1) Check what's directly in the camera's field of view. Is it a glass windowpane, a shiny appliance, or a picture frame? 2) Reposition the camera so its lens is either right up against the window glass (to avoid a reflection gap) or angled so it's not pointing directly at a reflective surface. 3) You can also try turning off the IR lights in the camera's settings and using an external, dim ambient light in the room instead.
IF THAT DIDN'T WORK: If the camera is in a corner pointing across a room, sometimes dust or a tiny spiderweb on the lens housing can scatter the IR light. Give the lens area a careful cleaning with compressed air and a microfiber cloth as described in the cleaning question.
HEADS UP: The Blink Mini 2 has a physical IR cut filter that switches on and off. You might hear a faint *click* when night vision engages; that's normal. If you're mounting it outdoors (not recommended unless in a weather-resistant case), condensation inside a window can also cause this blurry blob effect.