WH1TEG0LD

I have a 2009 Outback. It has recently had a new engine put in (ej25). After about a month, the belts started squeeking and when I turn the engine off, after about 10 seconds there is a loud screech coming from the rear of the engine. Sometimes this noise is instant. Im hoping someone could tell me whats causing this. Thanks in advance. Video in link. https://streamable.com/p2tw4b