How to stop shadows making a grid effect when cubes stacked together in a wall

I am making a game where players create vehicles from blocks.

When the blocks are put together, from certain angles you can see lines where the blocks meet, which makes a grid pattern.

It is something to do with the shadows, as the lines appear when the wall is rotated so that it is nearly inline with the direction of the light from the light source.

I am using URP, but before when I was using the standard system I had the same issue.

I tried to do some tweaking of settings, and it seems to be due to the URP shadows settings. Specifically the light source settings. I adjusted the depth value of the real time shadow bias, which reduced the problem.

However, I had to increase it quite a way, so now the shadows look very strange for everything else, and things looks like they are floating above surfaces and the ground.

Is there any other way that I can get rid of the grid effect caused by the block's shadows?

Appreciate the help.

Here is an image of the grid effect: