The short answer
Use SVG for logos, icons, and vector artwork that must scale cleanly. Use PNG for screenshots, raster graphics, transparent images, and upload forms that do not accept SVG.
If an app rejects SVG, convert SVG to PNG and choose a size large enough for the final destination.
When PNG is better
PNG is safer for forms, CMS uploads, social previews, screenshots, and tools that expect a normal image file. It preserves transparency and sharp edges, but it is pixel-based and can become blurry if enlarged too much.
When SVG is better
SVG is better for editable vector logos, icons, diagrams, and artwork that needs to scale without losing quality. Keep the SVG source even if you export a PNG copy for upload.