New clicking/tapping sound

As the title suggests, I started my car up tonight, only to be greeted by a lovely new sound. Truck is a 2010 with 150k miles.

Appears to be worse when cold, better when at operating temp. Slight increase in speed when revved up but not a rapid increase like with rod knock or the likes. It appears to go away briefly, say 1-3 seconds, then will continue again for a while longer. There doesn’t seem to be a prominent rhyme to its rhythm. The sound is more prominent from the front driver side of the engine.

Unknown service history. I’ve had the truck for a little less than 3k miles. Hasn’t had its first oil change with me. Only engine related work I’ve done to it is new cats/02 sensors by an independent shop and new ac compressor done by a Toyota dealership.

Any help or knowledge on the matter would be great. Thanks!

https://youtu.be/cLPnEvR9LqE video of noise.

 

Update (and I’m sure it’ll happen again), but the sound is gone. Went to start it up this morning to try and prod some more after someone locally said to look over the serpentine system. I’ll keep this thread posted with any future updates.

 

I've had a serpentine belt make similar noise.

 

Belt was only replaced 1,000 miles ago. If that. I wonder if its one of the pulleys or something