This has no mound, just a perfect hole, edge of border and grass but in border. Some sort of animal dog very interested
It could be voles, rodents, chipmunks, etc. You can excavate into the hole to see if there are eggs or tunnels. Keep an eye out, especially early in the morning, and try to catch the animal coming or going to see what it is. These articles should help:
https://www.gardeningknowhow.com/lawn-care/lgen/lawn-and-garden-holes.htm
https://www.gardeningknowhow.com/plant-problems/pests/animals/vole-control.htm
https://www.gardeningknowhow.com/plant-problems/pests/animals/chipmunk-control.htm
New Lawn was laid In August last year with at least 6 to 8” of fresh soil after digging out old clay/dirt .
Do you have a dog or does a neighbor dog visit? Brown spots with green edges can indicate dog urine. If not, it is likely a fungal disease. The yard in general looks like there are brown spots. These articles should help pin the problem down:
https://www.gardeningknowhow.com/lawn-care/lgen/dog-urine-grass.htm
https://www.gardeningknowhow.com/lawn-care/lgen/reasons-for-dying-grass.htm
https://www.gardeningknowhow.com/lawn-care/lgen/grass-fungus.htm
https://www.gardeningknowhow.com/lawn-care/lgen/brown-lawn-fixes.htm
The pictures are enclosed for perusal.
There are several possibilities. Check for webworms if you have them in your location. Here is info on webworms and on lawn diseases that should help.
https://www.gardeningknowhow.com/lawn-care/lgen/tropical-sod-webworm-control.htm
https://www.gardeningknowhow.com/lawn-care/lgen/treating-lawn-diseases.htm
https://www.gardeningknowhow.com/lawn-care/lgen/brown-lawn-fixes.htm
https://www.gardeningknowhow.com/lawn-care/lgen/lawn-grass-rust-fungus.htm