Export rendering artifacts

In the live preview and after exporting images, a glitchy border or semi-transparent halo appears around the screenshot element. This artifact seems to be generated during the export process and is not present in my original source images.

I’ve attached a comparison:

• Top image (Source): My original screenshot in Affinity on a flat background (Clean edges).

• Middle image (Export): The Postspark output (Visible edge artifacts).

• Bottom image (Live Preview): Visible edge artifacts all around screenshot except at corner radius.

I really hope this can be looked into so I can make the app my daily driver (as a lifetime user). Thanks!