Ability for enable smooth in a Line Source and blending problems

In Line Source editor is no option for enable smooth. We can do it by copying lfo with smooth option but can’t copy Line Source to Lfo. Also the blend options works improperly when one of the keyframes is smooth but second not. https://vitalpublic.s3.dualstack.us-west-2.amazonaws.com/original/2X/8/836a4229fdf80f5477fd290f16114d348f1ebba7.mp4