Help: Why does my thrifted Levi's 501 jacket keep showing a yellow stain that won't wash out?

I recently bought a thrifted Levi's 501 jacket from a local consignment shop. The jacket is in good shape overall, but there's a stubborn yellow spot on the left sleeve that just won't come out, no matter what I try.

I ran it through a standard cycle with 30°C water, a regular detergent, and a normal spin. I even added a bit of bleach (just 1/4 cup) because the instructions say it can help with yellowing.

After the first wash the spot was still there, but the rest of the jacket looked fine. I tried a second wash with a stronger detergent (Tide Ultra) and a 40°C cycle, but the spot remained. I even used a pre‑treatment spray (OxiClean) and left it soaking for 30 minutes before washing.

I also tried soaking the jacket in a homemade solution of vinegar and baking soda for an hour, but the yellow stain still persisted.

The only thing that seemed to change was that after adding bleach, the jacket turned a faint greenish tint around the edges, which I think is because the fabric is old cotton and the bleach reacted.

Does anyone else have a similar experience with old Levi's 501s? Are there any specific cleaning methods or products that work better for these kinds of stains? I’m worried that if I keep using bleach it might ruin the jacket.

Any advice would be appreciated. Thanks!