Outside of the obvious war, Kaliningrad in certain conditions. If you have local friends there you trust, or you are fluent in Russian, you'll have a great time. Its got a lot of nice history, some nice views, and its cheap. But if you're an obvious tourist, they do not treat you kindly. I wore a tank top and shorts in the city on my way from Svetlagorst beach and got side eyes for my tattoos and attire. If you're used to stereotypically polite service, it's not as prevalent there in Russia. And if you try to be nice, you're seen as a weirdo.
Lithuania is also hit or miss. Vilnius and Klaipeda are nice, but are NOT tourist friendly. I used to live there, but when I went back as a kid, my mom and I spoke English and Russian. They tried to overcharge our meal significantly but my mom knowing Lithuanian caught it. The people at the corner store also questioned why I only speak Russian, and hesitantly spoke with me. Plus people on the street would call out appearances if you look different. Really good fuckin pizza though