Avoid pinching due to mirror the mirror modifier create pinching when mirroring a curve surface is there a way to avoid it ?

even with a flat surface on the inner edge of the mesh there is still pinching
Just in case somebody comes across this thread looking for the answer (because I believe OP is no longer waiting for one): If you have a SubDivision modifier, it should come AFTER the Mirror modifier, so that the transition gets smoothed.