The only real way forward with this is to make detailed close-ups of the damage, to see if it is restricted to one flank or both, and during the play of the fish, to note if there is any jerking or jinking that might be leader wrap in the fins.
The fact that some of us see very minor damage, and some see deep scarring shows we need to make notes on the type of damage at the time of capture, and record it with decent macro shots.
Without this it is all interesting conjecture.
For sure. It was only when I gradually became aware of taking photos of fish showing damage in the same place that I put the gallery together. I will go back to the originals and do some zooming in. No point in anyone trying to enlarge the shots in the OP, as they are all 1500 pixel down-sizes and you will not get any extra detail out of them buy trying to enlarge them. But the originals are mostly 31 megapixels, and I can do a bit of genuine zooming in on them at my end.
And I will certainly be looking out for this in future - including checking both sides of the fish.