Terrified of going out at night

I’ve had my dog (~3, spayed, Chiweenie) for almost 2 years. Her confidence has increased immensely in that time. She’s a great walker. I wouldn’t say she’s the most social dog but in the way where on a walk she doesn’t react to every dog and doesn’t feel the need to meet every dog. If she doesn’t want to she just keeps walking and ignores it, but if she does she just does a sniff greet and is ready to move on. She’s only a little skittish when strangers approach too fast wanting to pet her. She goes to school (daycare) a couple times a week to keep her social.

We live in an apartment and doesn’t have problems going outside for walks or potty breaks. Recently, during her last call before bed, she’s been absolutely terrified of going outside. I have no idea why. She hasn’t had any bad interactions with any other dogs, animals, or people in the neighborhood and her teachers at school haven’t noticed any change in her behavior, but every night as soon as we close the door she starts freaking out. She shakes, constantly looks over her shoulder like something is going to get her, and wants to go back inside immediately. If she sees another dog or person regardless of if they’re walking towards us, away, or are on their own patios, she starts trying to escape her leash and tries running back to the house.

I’m not sure how to help her overcome this fear. I’ve been bringing her favorite treats with us to motivate her, but she either scarfs it down while trying to get out of the leash or just won’t eat it because she’s too scared to move. She doesn’t have any type of comfort toy or item that she could bring with her, but even if she did she doesn’t like to carry her own stuff on walks and would rather leave it behind than carry it herself. I’ve tried timing it so she doesn’t have to see or interact with any other living thing, but that doesn’t change how she’s acting.

Any advice, suggestions, or things that have worked for other owners of anxious/timid/easily scared or stressed dogs would be greatly appreciated. I don’t want my baby regressing anymore to the point she’s afraid to go outside at any time of day.