I am interested in joining this game jam though I use unreal engine 5 and haven't found and games using the engine yet. so I was wondering if it would be aloud to switch a games engine or if I should just look for a different game jam

I am no expert but I think taking a game from one engine and transfering it to another one is doable, but necessitate a lot of time and effort. Not worth it for this jam as you wouldn't have time to do much, if anything to the game you pick.
A shame we didn't see many Unreal engine games during the jam.

Yeah i agree ^

It's doable, it's not against the rules - but its a lot of work, may change the game significantly or introduce unique hurdles (if you are not very familiar with both engines), and most importantly - a waste of valuable valuable time.

You absolutely can switch engines if you know them just pick any project you want to work on. You can also take a look at GDevelop projects here https://itch.io/jam/day-4/topic/3024983/gdevelop-community

I did it day 2.. although i pretty much just stole the assets and did a new game. But I reckon you can do whatever you want with the project during your day of working on it :)