A rusted out floor pan "repair"? Looks like he secured a new pan or sheet metal piece with a sheet metal screw then tried welding the rust back to the underside to "secure" it permanently & keep it from spinning around on the inside.
Agreed it is unbelievably inept. However, you can't blame a guy for trying. If I never had picked up welder and tried, I might have done something similar........ Nah, I'd have probably done better. If my 6 year old grandson never had picked up welder and tried, he might have done something similar.
I worked with a guy in maintenance dept that thought he was a heck of a welder, He would fill in bad spots with silicone caulk and paint with silver paint when no one was watching. He finally went on to another line of work.