About a month ago I replaced my valve cover gasket, however I noticed while doing so that the timing chain seemed a bit loose. I didn’t do much at the time and kept driving. I now hear a light rattling noise at certain RPMs and I wanted to see if I could get a look at the chain through the oil fill cap. I took the cap off while running and I hear a deep erratic rattling, is this the chain or something worse, and can it be solved with a new tensioner spring?

Here is a video of the noise:
https://youtu.be/H2-zOs3qKIc