You need to calibrate for your typical / expected angle or if you don’t have one then for the middle of the range.
This is one of the limiting factors on how accurate you can get the final position. In theory if you know the orientation of the anchors and the tag location then you can calculate and correct for the anchor antennas. For the tag you need to either use an average value or if you can infer orientation from direction of travel you can correct for it using that.
Or you go the route we picked and use a different antenna