This is not a great photo by any means, but does highliight the issue, top left corner.
In a case like this one I can of course copy a neighbouring spot, paste it on top on the in-perfection, and presto, but most of the time the image is not uniform in color...
I did use second layers, bopy similar color on the extra layer, and blur the edges so it would fit in descently well, but I'm wondering if there is not a more adapted tool/technique
Regs