documentclass{article}
usepackage{calc}
usepackage{tikz}
usetikzlibrary{hobby, arrows.meta,bending}

newcommand*{jdx}[1][1]{%
begin{tikzpicture}[baseline, xscale=#1]
draw[black, {Round Cap}-{To[angle=90:.3cm 1,length=9mm, flex'=.86]}, line width=4pt] (.1,.85) to [curve through={(.79,.18) .. (1.45,.7) .. (1.2,1.6) .. (.9,1.6) .. (1.9,1.6)}]
(2.1,2.5);
node[red, circle, draw, text width=10pt] at (.1,.85) {};
end{tikzpicture}}

newcommand*{gapdx}[1][1]{%
begin{tikzpicture}[baseline, xscale=#1]
draw[black, {Round Cap}-{To[angle=90:.3cm 1,length=9mm, flex'=.86]}, line width=4pt] (.1,.85) to [curve through={(.79,.18) .. (1.45,.7)
(1.48,.8) ..
([blank=soft]1.43,1.4)
.. (1.2,1.6) .. (.9,1.6) .. (1.9,1.6)}]
(2.1,2.5);
node[red, circle, draw, text width=10pt] at (.1,.85) {};
node[blue, circle, draw, text width=10pt] at (1.43,1.4) {};
end{tikzpicture}}


begin{document}
Without verb|[blank=soft]| is OK:

jdx

With verb|[blank=soft]| the rounded end is not where I need it, here I want a rounded end where there is the red circle and a sharp end where there is the blue one:

gapdx

end{document}

documentclass{article}
usepackage{calc}
usepackage{tikz}
usetikzlibrary{hobby, arrows.meta,bending}

newcommand*{jdx}[1][1]{%
begin{tikzpicture}[baseline, xscale=#1]
draw[black, {Round Cap}-{To[angle=90:.3cm 1,length=9mm, flex'=.86]}, line width=4pt] (.1,.85) to [curve through={(.79,.18) .. (1.45,.7) .. (1.2,1.6) .. (.9,1.6) .. (1.9,1.6)}]
(2.1,2.5);
node[red, circle, draw, text width=10pt] at (.1,.85) {};
end{tikzpicture}}

newcommand*{gapdx}[1][1]{%
begin{tikzpicture}[baseline, xscale=#1]
draw[black,line cap=round, -{To[angle=90:.3cm 1,length=9mm, flex'=.86]}, line width=4pt] (.1,.85) to [curve through={(.79,.18) .. (1.45,.7)
(1.48,.8) ..
([blank=soft]1.43,1.4)
.. (1.2,1.6) .. (.9,1.6) .. (1.9,1.6)}]
(2.1,2.5);
node[red, circle, draw, text width=10pt] at (.1,.85) {};
end{tikzpicture}}


begin{document}
Without verb|[blank=soft]|:

jdx

With verb|[blank=soft]|:

gapdx

end{document}

documentclass{article}
usepackage{calc}
usepackage{tikz}
usetikzlibrary{hobby, arrows.meta,bending}

newcommand*{jdx}[1][1]{%
begin{tikzpicture}[baseline, xscale=#1]
draw[black, {Round Cap}-{To[angle=90:.3cm 1,length=9mm, flex'=.86]}, line width=4pt] (.1,.85) to [curve through={(.79,.18) .. (1.45,.7) .. (1.2,1.6) .. (.9,1.6) .. (1.9,1.6)}]
(2.1,2.5);
node[red, circle, draw, text width=10pt] at (.1,.85) {};
end{tikzpicture}}

newcommand*{gapdx}[1][1]{%
begin{tikzpicture}[baseline, xscale=#1]
draw[black, -{To[angle=90:.3cm 1,length=9mm, flex'=.86]}, line width=4pt] (.1,.85) to [curve through={(.79,.18) .. (1.45,.7) (1.48,.8) .. ([blank=soft]1.43,1.4) .. (1.2,1.6) .. (.9,1.6) .. (1.9,1.6)}]
(2.1,2.5);
fill (.1,.85) circle (2pt);
node[red, circle, draw, text width=10pt] at (.1,.85) {};
end{tikzpicture}}


begin{document}
Without verb|[blank=soft]|:

jdx

With verb|[blank=soft]|:

gapdx

end{document}

documentclass{article}
usepackage{tikz}
usetikzlibrary{hobby, arrows.meta,bending,decorations.markings}

newcommand*{jdx}[1][1]{%
begin{tikzpicture}[baseline, xscale=#1]
draw[black, {Round Cap}-{To[angle=90:.3cm 1,length=9mm, flex'=.86]}, line width=4pt] (.1,.85) to [curve through={(.79,.18) .. (1.45,.7) .. (1.2,1.6) .. (.9,1.6) .. (1.9,1.6)}]
(2.1,2.5);
node[red, circle, draw, text width=10pt] at (.1,.85) {};
end{tikzpicture}}

newcommand*{gapdx}[1][1]{%
begin{tikzpicture}[baseline, xscale=#1]
draw[black, -{To[angle=90:.3cm 1,length=9mm, flex'=.86]}, line width=4pt,
postaction={decorate,
decoration={markings,mark=at position 0 with {fill (0,0) circle (2pt) ;}}
}] (.1,.85) to [curve through={(.79,.18) .. (1.45,.7)
(1.48,.8) ..
([blank=soft]1.43,1.4)
.. (1.2,1.6) .. (.9,1.6) .. (1.9,1.6)}]
(2.1,2.5);
node[red, circle, draw, text width=10pt] at (.1,.85) {};
node[blue, circle, draw, text width=10pt] at (1.43,1.4) {};
end{tikzpicture}}


newcommand*{standardz}[1][1]{%
begin{tikzpicture}[baseline, xscale=#1]
draw[black, {Round Cap}-{To[angle=90:.3cm 1,length=9mm, flex'=.86]},
line width=4pt]
(.1,.85) to[bend right]
(1.48,.8)
(1.43,1.4) to[bend right] (2.1,2.5);
node[red, circle, draw, text width=10pt] at (.1,.85) {};
node[blue, circle, draw, text width=10pt] at (1.43,1.4) {};
end{tikzpicture}}


begin{document}
Without verb|[blank=soft]| on has one path, and the arrow heads are in the
beginning and at the end of the path:

jdx

Standard Tiemph{k}Z behavior: whenever there is a gap in the path, the arrow
heads are attached at the last stretch.

standardz


The Hobby paths do not behave differently. If you want to add a round line cap
at the beginning, you may just use decorations, which affect the whole path.

gapdx

end{document}