Why is my grass growing better in patches

Interesting theory. When I was younger, we had 5 big dogs and they killed the lawn wherever they peed. So that's a possibility.

Another possibility would be that around the stones and edges, there are other (better?) Nutrients and the soil composition is not to the lawns liking.

I remember Back in 2019 when there was widespread draught lots of old bronze age ruins showed up on the previously normal landscape. The grass didn't grow as well on places that once were occupied by buildings and walls. The buildings themselves deteriorated hundreds or even thousands of years ago, but the stone used to build them remained a few centimetres below the surface. Normally you wouldn't notice, but during a draught those placed got less moisture from deep underground and the plants grew punier than around them leaving markings that could be seen from above.
Long story short - maybe someone dumped a lot of rubble, trash or even remains from the building before yours in the lawn because "no one will ever find out".

Edit: other way around might also be possible. Around the edges and next to the stones, water can drain better because there is sand and gravel beneath the surface, whereas in the middle of the lawn, the soil turns to mush and roots start to rot, reducing growth.

 

I'd try a light sprinkling watered in well,don't think it would do any real harm.