hi mindthegap first convert to dds format, with the texture converter ( in contributions) and see if it works: png is more heavy than dds, and you texture needs all to be in fact in a 8 multiplier length ( 64128, 1440 * 1080 or what else)
I can add to this, I have similar experience with with png’s and DDS files. I have hunted the behavior down to when the edge of a transparent layer is not aligned with the pixel grid of the renderer. see attached patch.
this is the normal behavior of linear texture sampling, its independent from the file format. if you interpolate from transparent to non transparent you get pixels which have an alpha value between 0 and 1 and the color channels of the transparent part of the texture become visible at that position.
to avoid this you can quantise the position in pixel space with a frac, or you set the texture filtering to nearest neighbour, scaling the texture is of course not a good idea in this scenario: