Point lights and spot lights do not change the size of the light source due to scaling, only the lighting effects of area lights are affected by scaling. If you need to change the size of a point light or spotlight, select the light and go to the interface of the light bulb-shaped icon in the properties panel. This is not a bug.

In T101557#1426580, @liang yunfei (LemonBranny) wrote:

Point lights and spot lights do not change the size of the light source due to scaling, only the lighting effects of area lights are affected by scaling. If you need to change the size of a point light or spotlight, select the light and go to the interface of the light bulb-shaped icon in the properties panel. This is not a bug.

我知道在灯光属性里面调节spot size可以控制，但从视觉常识上来讲，spot lamp的边界线（限制范围）如果收缩或者放大，理应控制spot size的大小，Eevee引擎上就做得很好。

我知道在灯光属性里面调节spot size可以控制，但从视觉常识上来讲，spot lamp的边界线（限制范围）如果收缩或者放大，理应控制spot size的大小，Eevee引擎上就做得很好。

If you want to change the spread angle of the spotlight beam, you can do so by dragging the arrow shape of the spotlight in the viewport. The effect achieved by zooming in eevee is no different from this operation.

In T101557#1426586, @liang yunfei (LemonBranny) wrote:

我知道在灯光属性里面调节spot size可以控制，但从视觉常识上来讲，spot lamp的边界线（限制范围）如果收缩或者放大，理应控制spot size的大小，Eevee引擎上就做得很好。

If you want to change the spread angle of the spotlight beam, you can do so by dragging the arrow shape of the spotlight in the viewport. The effect achieved by zooming in eevee is no different from this operation.

If I want change the spread angle of the spot light beam in geometry nodes, so how can I do that? In eevee render, I can scale, but in cycles I can do nothing. it's still not a bug?

This is the same bug reported and confirmed at https://developer.blender.org/T76823
So it's a duplicate.
I'll merge the reports...