We don't have fruit borers here in Wyoming. Well, if we do, I haven't seen 'em yet. I do have damage like that, Nes. They are generally blemishes, probably caused by birds or hail or something like that requiring the tomato to develop scar tissue to protect the inner flesh. In fact, there is a gang of pigeon thugs that roam my streets, and I suspect they keep checking my tomatoes to see whether they have turned to dried grain yet. Oh. I bet insect eaters leave a mark when they snag a worm or whatever. Also, because I use cages to support my tomatoes, several of them have blemishes from having come into contact with the cage bars (?) while maturing. No big deal. It all tastes good
That's a lovely first tomato, by the way!