I think we have found a small bug with the default plane in Playcanvas and his tiling.
When I put this image on a plane in the editor (note the blue on one side only),
we got an undesired blue line at the other edge of that plane:
But, if we change the tiling a little bit, the problem go away:
Try setting your texture asset address UV from repeat to clamp (appearing on the inspector when you select your image in the asset window).
That will resolve your issue, if you are using a non repeating texture.
Yeah! That solved my problem! Thank you!