Downloaded PNG in RGB mode fails to support transparency: erase uses secondary color and export PNG replaces transparent color with black about aseprite HOT 2 OPEN

Thanks for this report. Some comments:
Some PNG images were loaded with a Background layer (instead a regular transparent layer) according how the images were encoded.

When you have a Backgroud layer, all pixels on your canvas will be non transparent and the eraser tool will 'paint':

• left click: the secondary color (bg color)
• right click: only the primary color will be replaced with secondary color within applied eraser area.

To work with pixels with alpha values, convert the 'Background Layer' to 'Layer': right click on Layer name, Convert to... > Layer

Just in case: to select all the color you need to remove, the best tool is 'Magic Wand' with 0 Tolerance and Continuos unchecked on the context bar ('continuos unchecked' will remove isolated areas of color too).

More info about Background Layer: https://aseprite.org/docs/layers#background-layer

from aseprite.

Based on your Repro steps, I see the inconsistency: there may be transparent pixels on a Background Layer, which should be prohibited. Then, in the export process, the alpha content of the pixels is discarded since the layer is a background layer. That's why it turns out 6. Export PNG => background is now black

from aseprite.