Hello. I have an issue with the snakes. I made a terrarium in one of my homes and I had a snake in the terrarium. After the first time the snake despawned. I summoned and placed the new snake in the terrarium and this time I named him. I went away from the terrarium for a while, but when I came back to the terrarium, the snake despawned again. I think he died, because the snake left a snake skin. Idk what's causing this issue. Maybe it has to do with the plants I use for decorating the terrarium? I have 2 Glowberries vines and one stem of Dripleaf. Is the lack of space causing this issue? The terrarium is 3 by 1 blocks and it is built in the wall. Do I need a burrow for the snake from despawning? This doesn't happen to the soft shell turtles, only the snakes. Plzz HeLp!!!1!!!!

Mobs do not despawn under any circumstance (exception being mobs belonging to a burrow, kinda). There's also a notorious, rare bug in vanilla where a mob close to a wall may suffocate in solid walls: MC-2025

That said, the most likely explanation is that some hostile mob spawned/made its way inside the terrarium and angered the snake, which attacked it and got killed