Old fuel disposal or use ?

My dart sat for 4 plus years in the garage in California. No special treatment was done. It started right up.
I added 3/4 tank of new gas, ran it till empty, another full tank, ran till empty.

That was in 2017
This was the inside of my tank in 2021


View attachment 1716048472

View attachment 1716048473
(Yes that was a piece of duct tape I was retrieving)


Your results may very.
HOW did you get in there??