ffmpeg – lossless image rotation

I am trying to add a transparent image (png) (that I would like to rotate – amongst other things…) over another image (jpeg).

Here is the result (left = non rotated, right = rotated):

As you can see, the rotation causes the png to bleed. Do you have any idea how to improve the output (I also tried the bilinear option of the rotate filter) ?
Here is the ffmpeg command:

 ffmpeg -y -vsync 0 -i background.jpeg -loop 1 -pix_fmt rgba -i button.png -filter_complex "[1]setsar=1,rotate=a=PI/6:c=none:ow=rotw(PI/6):oh=roth(PI/6)[s1];[0][s1]overlay=x=100:y=100[s2]" -map "[s2]" -c:v libx264 -crf 0 -pix_fmt yuv420p -t 5 video.mp4 -hide_banner