If you aren't rendering at a size that matches the source images then it is expected that there will be some filtering artifacts. The smoothing settings in v4 provide some control over this. It used to be only nearest or linear, now it we have 5 levels of smoothing:
0: nearest (no smoothing)
1: bilinear (light)
2: bilinear (medium)
3: bilinear (normal, equivalent to linear in Spine <= 3.8)
3: bicubic (like bilinear but less square/star artifacts)
Additionally we now have a Keep edges checkbox for the viewport (not exports) that keeps the original alpha values. This allows you to use smoothing so images look nicer when zoomed it, but without losing the ability to see exactly where the edges of your images are. Without Keep edges the edges are smoothed and tend to become blurry.
How does your text look (in exports and viewport) at various levels of smoothing, or 0?
