Voice-of-Shadow Sorry for the trouble! After checking, it seems that this is a bug that occurred in 4.3.21-beta. Several improvements related to weights were added in 4.3.21-beta, so this issue may have occurred at that time.

I have created a ticket to address the problem here:
EsotericSoftware/spine-editor907
Thank you so much for reporting the issue!

Hi, this bug appears in the latest official build (4.2.42 released on May 21). If the full 4.3 release is still some way off, please fix it promptly. The bug is still triggered by selecting frame 0 with the UI scaled down.

It was reported and an issue created, but I wasn't able to reproduce it:
EsotericSoftware/spine-editor895
I see now that it happens only when the view width is narrow. We'll fix it for 4.2.43. I am sad that 4.2.42 won't be the final 4.2 version number.

Voice-of-Shadow Thank you for explaining the situation. If the colleague who will be responsible for the follow-up work is the person in charge of HTML implementation, please encourage them to post their questions about the implementation method on the forum. Advice on run-time issues may vary greatly depending on the Spine runtime used, so it is difficult to provide advice without knowing the specific implementation plan. It is also preferable that the person responsible for implementation ask such questions.

Voice-of-Shadow Are you referring to this kind of appearance?:

Unfortunately, it is not possible to avoid the issue where overlapping areas of other attachments become opaque when each image attachment is made semi-transparent using only the Spine Editor. If the final product is a video, you will need to export the animation created in Spine and then apply the semi-transparent effect using video editing software. If such an effect is required at runtime, you will need to consider a workaround tailored to each runtime environment. Currently, in the spine-unity runtime, there is a relatively simple method to work around this issue using Unity's RenderTexture.

如果用裁切的话、裁切的硬边缘不好处理。

Similarly, if the finished product is a video, it must be processed using video editing software, or if the effect is needed at runtime, it must be processed using shaders at runtime.

某个项目无法换成100%不透明度的正常图层模式。因为阴影下面映照着纹理着地面的纹理。而正片叠底的部件是人物交替脚的阴影。

I am afraid I am not sure what the problem is in this section. It would be helpful if you could provide an example image to clarify.

Voice-of-Shadow Thanks for the additional information! I was able to reproduce the problem, so we have created an issue for a fix:
EsotericSoftware/spine-editor886