Sellotape caused discoloration on the wooden surface
hard to tell from the photo, but I think you have old varnish, just aged and oxidized.  take some acetone and wipe the area at the edge of the ripped area.  if you wipe it and get some yellowy residue, you probably have old varnish or lacquer.  if not, wipe with methanol or methyl hydrate.  if this produces yellowy residue, you have old shellac.  if it doesn't wipe with either process you may have a urethane that's tinted and it would need sanding and refinishing.

either way, if it wipes off with either chemical, just wet feather the edge and then let dry.  you should see a lighter area when it dries, but with a smooth transition.  then you can topcoat.  don't try to match colours as the area will naturally darken in the stripped wood section when you coat it, and then further as it ages.