Thanks for the testing.
The problem happened on external 4k monitor (Dell u2720qm). Try rotate the viewport, the default scene with a single cube is laggy enough to notice.

Same issue here, Blender 3.0 apple sillicon version on macOS Monterey 12.1

But why the shadow that soft?

Some objects in the scene will cause such problem. After deleting them, the 3d cursor grid snap back to normal. If ctrl-z to add them back, the weird snapping would appear again.

In T77375#944967, @NXSK (NXSK) wrote:

In T77375#944956, @Fei Bao (bao007fei) wrote:

In T77375#944924, @NXSK (NXSK) wrote:

In T77375#944922, @Fei Bao (bao007fei) wrote:

@NXSK (NXSK)

Only one HDR image for light, primitive sphere with smooth shade, looks fine.

Make sure to use Catmull-Clark type instead of Simple type.

No. This is nothing to do with the subdivision surface modifier. If the normal is smoothed, the shading from viewer angle should be smooth, without any light breakups.

I think it might be the problem that robert says. And this issue might be there for a long time.

For your situation, only one HDR for light. I tried and don't see any light break problem. Maybe the texture is not perfectly seamless?
For me it only appear for built-in lights with low subdivision geometry.

My texture is procedual. Some simple material won't show this issue.

And I'm curious about my previous work: a game flash light with low poly counts. Without normal map it still looks fine. But a sphere with a procedual carbon weave, it looks ugly, even if it is subdivided, just the jagged "teeth" becomes denser.

I asked my friends about this issue. They say Radeon Prorender and Octane render have the same issue. I think this might be the problem of path tracing shading algorithm.

In T77375#944920, @Robert Guetzkow (rjg) wrote:

This looks like the shadow terminator problem to me. In 2.90 there will be an option to shift the terminator towards the light source, hiding the artifacts at the cost of realism and lack of energy conservation. See rBc7280ce65b856d26d6807c1b7a081ffc6311bfdc and D7634

In T77375#944924, @NXSK (NXSK) wrote:

In T77375#944922, @Fei Bao (bao007fei) wrote:

@NXSK (NXSK)

Only one HDR image for light, primitive sphere with smooth shade, looks fine.

Make sure to use Catmull-Clark type instead of Simple type.

No. This is nothing to do with the subdivision surface modifier. If the normal is smoothed, the shading from viewer angle should be smooth, without any light breakups.

I think it might be the problem that robert says. And this issue might be there for a long time.

@NXSK (NXSK)