I re-installed new tires for the first time yesterday. Now I'm having problems with my rear derailleur. The chain keeps popping off the derailleur guide pulley when I pedal forward. I can re-seat it easily but it just keeps popping off. Pics (and a video) below.
Disclaimer: this is a piece of crap bike that I got for free so thats why it looks like garbage. Also I am new to bike repair so I almost certainly did multiple things wrong 🙃