FattyJoker Unfortunately, it is difficult to determine the cause based on this information alone. Please check the following:
Select the SkeletonDataAsset for that skeleton and check whether the skeleton is displayed correctly in the Preview section at the bottom of the Inspector window. If it appears correctly in the Preview, the issue may be related to your implementation.

In that case, please send us a minimal Unity project that reproduces the issue via email at contact@esotericsoftware.com.
Please include the URL of this forum thread in the email so we know the context. Then we can take a look at what's wrong.

If the skeleton does not display correctly even in the Preview, the settings for exporting from Spine may not be appropriate. Please show us the settings in the export window and the texture packer settings window.

FattyJoker What exactly do you mean by "distorted", do you mean the mesh edges should be straight downward? Could you show a second image of the expected result, e.g. how it is supposed to look, e.g. in the Spine Editor. Please note that we don't know your project.

Are you using Physics Constraints at your flag?
Regarding your export and import settings: did you also enable Straight alpha texture at the Material?

My Unity version is 2021.3.41f.
Spine version is 4.2.18

What exact version of the spine-unity runtime (name of the unitypackage, also listed in Assets/Spine/version.txt, or in the Package Manager) are you usiung?

FattyJoker The settings you showed us appear to be normal, so it might be best to send us the Spine project file so we can confirm what the expected results should be. Could you please include the link to this thread in the body of your email and attach the relevant Spine project file?: contact@esotericsoftware.com

FattyJoker I see. Based on that information, it may be a quality setting issue. When building for iOS or Android in Unity, the quality settings may be adjusted to match the target platform, which could lower the anti-aliasing level or change settings such as anisotropic textures, thereby altering how the edges appear. Could you please review them and see if the problem is resolved?

@FattyJoker I'm not sure I understand exactly where you are encountering the above issue. Do you mean that the SkeletonAnimation preview shows a correct result at the following combination:

• Editor runnining on MAC, Active Target iOS - distortion visible in the Unity Editor.
• Editor runnining on Windows PC, Active Target iOS - correct display in the Unity Editor.

To be more precise: in the distorted case, where exactly do you see the distortion: In the Scene view, in the Game view, in the Preview panel?

My guess its that the machines where the issue is visible are either a) rendering at higher resolution and thus sampling artifacts occur, or b) thetextures are resized differently on the problematic platforms.

Also ensure that Game view is set to 1x zoom and not something like 1.5x.

FattyJoker It is difficult for us to identify the cause based on speculation alone, so we would appreciate it if you could create a minimal Unity project that reproduces the problem and send it to us via email: contact@esotericsoftware.com
Please include the URL of this forum thread in the email so we know the context. Then we can take a look at what's wrong.

FattyJoker Thank you for sending us an email. I checked our inbox, but it seems that we have not received your email yet. Just to be sure, did you send it today?

FattyJoker Thank you for resending it! We received your email.

However, what you sent us was a Spine project file, not a Unity project file, and the contents were not minimal at all.
Even so, I exported the Spine project you sent me, imported it into a new URP project, set the build target to iOS, and checked the animation, but I couldn't reproduce the problem. (I am using a Mac PC.)
I sent you a video of the test results as evidence via email. Please check it.

Please review your settings again based on these results or send us a minimal Unity project that reproduces the problem: contact@esotericsoftware.com

FattyJoker Thank you for sending us the video and Unity project.
After reviewing them, we have confirmed that the issue occurs only when using SkeletonGraphic.
However, when testing a different Spine skeleton under similar conditions, we were unable to reproduce the same problem.

I also noticed that your skeleton shares textures with many others, resulting in a large combined texture size.
So, I tried exporting and importing only the relevant skeleton, and the edge distortion problem did not occur.

We will continue to investigate this matter further.