Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce RTX 2060/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.38
Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-10-05 08:29, hash: rBa4f8b2ad7653
Worked: (newest version of Blender that worked as expected)
Short description of error
Import via Image as Planes a transparent PNG as emit or shaderless and alpha mode as STRAIGHT (as it should be for a PNG).
In the viewport and in Eevee renders we can see white fringes in the transparency border. At the Image Editor, it is ok.
Cycles renders it correctly.
If we import as Premultiplied, the problem inverts: Not ok at Image Editor, ok in Eevee and viewport.