Sun bleached wood

I started a queen sized bed a few months ago and got 90% of the way done with it before I got distracted by other projects. The headboard sat leaning against the garage door for the last several months and I thought nothing of it. Yesterday I decided I was going to finish sanding the bed and get it done by the end of the month so I pulled it away from the door and found that a portion of the headboard had been bleached by the sun through the windows of the garage door.

I sanded it for a while today and there is still a color difference. I’m afraid to sand the panels much further because they’re sapele plywood and I don’t want to sand through to the substrate. Has anybody else ever had this happen? When I stain/shellac it, do you think it will still be noticeable?

-- I wish wood grew on trees so that this was a cheaper hobby.