@sloot  @Bruce Sterling @bruces @Derek Caelin is writing a book

For what it's worth, the yellow image was evidently first posted in March 2020: #^https://tineye.com/search/5e53be9cf7b26759e9f9eec9fe43611f42de5f7b?sort=score&order=desc&page=1

That doesn't rule out AI or photoshopping, but I guess it's useful to know.  Unfortunately I wasn't able to find any of those TineEye links that was still live.

What I had initially guessed about that yellow sign was that bits of paint had been lifted by the bark and somehow stayed on the surface as the tree continued to grow, but I don't know enough about bark growth to know if that makes any kind of sense.