[Bug] voltage shift is not consistent across components

[Rmano]

Reported on TeX.stackexchange by UserUnkn4wn

When used globally, voltage shift works in different ways for different components.

\documentclass{report}
\usepackage{graphicx} % Required for inserting images

\usepackage{tikz}
\usepackage[european,straightvoltages]{circuitikz}

\ctikzset{resistors/scale=0.55}
\ctikzset{inductors/scale=0.55}
\ctikzset{capacitors/scale=0.6}
\ctikzset{sources/scale=.8}
\ctikzset{bipoles/thickness=1}
\ctikzset{tripoles/thickness=1}
\tikzset{every picture/.style = {transform shape, line width=1pt}}

\begin{document}

\hbox{
    \begin{circuitikz}
     % Switch
    \draw (2,0) node[spdt, rotate=90,anchor=in] (sw) {};
    \draw (sw.out 2)  node[right] {(2)};
    \draw (sw.out 1)  node[left] {(1)};

     %Komponenen
    \draw (0.5,0)  to [V_=$U$] (0.5,-1);
    \draw (2,0) to [R,v=$U_R$] (2,-1) to [L,v=$U_L$] (2,-2);
    \draw (3.5,0) to [C,v=$U_C$] (3.5,-2);

     %Verkabelung
    \draw (0.5,0) to (0.5,1.5) -| (sw.out 1);
    \draw (3.5,0) to (3.5,1.5) -| (sw.out 2);
    \draw (2,-2) to (2,-2.5) -| (0.5,-1);
    \draw (3.5,-2) |- (2,-2.5) node[circ]{};

    \draw (4.5,1) [open,v=$U$] to (4.5,-2);
        
    \end{circuitikz}

    \hspace{2cm}
    
    \ctikzset{voltage shift = 2}
    \begin{circuitikz}
    % Switch
    \draw (2,0) node[spdt, rotate=90,anchor=in] (sw) {};
    \draw (sw.out 2)  node[right] {(2)};
    \draw (sw.out 1)  node[left] {(1)};

    %Komponenen
    \draw (0.5,0)  to [V_=$U$] (0.5,-1);
    \draw (2,0) to [R,v=$U_R$] (2,-1) to [L,v=$U_L$] (2,-2);
    \draw (3.5,0) to [C,v=$U_C$] (3.5,-2);

     %Verkabelung  
    \draw (0.5,0) to (0.5,1.5) -| (sw.out 1);
    \draw (3.5,0) to (3.5,1.5) -| (sw.out 2);
    \draw (2,-2) to (2,-2.5) -| (0.5,-1);
    \draw (3.5,-2) |- (2,-2.5) node[circ]{};

    \draw (4.5,1) [open,v=$U$] to (4.5,-2);
        
    \end{circuitikz}
}

\end{document}

Notice how the shift in the voltage source and the open arrow is wrong (too much).

[Rmano]

There are clearly two issues here: one is the one spotted on TeX.SX, the other one is that there is something going awry with the open voltage positioning (they are interwined with the additional shift and they shouldn't):

\documentclass[border=3mm]{standalone}
\usepackage{graphicx} % Required for inserting images
\usepackage{etoolbox}

\usepackage[european,straightvoltages]{circuitikz}
\makeatletter
\iftrue
\patchcmd{\pgf@circ@drawvoltagegenerator}
    {\pgfmathsetmacro{\bumpaplus}{\bumpa + 0.5*\shiftv}}
    {\pgfmathsetmacro{\bumpaplus}{\bumpa + 0.3*\shiftv}}
    {\relax}{\ERROR}
\fi
\makeatother
% \ctikzset{resistors/scale=0.55}
% \ctikzset{inductors/scale=0.55}
% \ctikzset{capacitors/scale=0.6}
% \ctikzset{sources/scale=.8}
% \ctikzset{bipoles/thickness=1}
% \ctikzset{tripoles/thickness=1}
% \tikzset{every picture/.style = {transform shape, line width=1pt}}

\newcommand{\circuit}{%
    \begin{circuitikz}[scale=2]
        % Switch
        \draw (2,0) node[spdt, rotate=90,anchor=in] (sw) {};
        \draw (sw.out 2)  node[right] {(2)};
        \draw (sw.out 1)  node[left] {(1)};
        %Komponenen
        \draw (0.5,0)  to [V_=$U$] (0.5,-1);
        \draw (2,0) to [R,v=$U_R$] (2,-1) to [L,v=$U_L$] (2,-2);
        \draw (3.5,0) to [C,v=$U_C$] (3.5,-2);
        %Verkabelung
        \draw (0.5,0) to (0.5,1.5) -| (sw.out 1);
        \draw (3.5,0) to (3.5,1.5) -| (sw.out 2);
        \draw (2,-2) to (2,-2.5) -| (0.5,-1);
        \draw (3.5,-2) |- (2,-2.5) node[circ]{};
        %
        \draw (4.5,1) [open,v=$U$] to (4.5,-2);
    \end{circuitikz}
}

\begin{document}

\circuit
\quad
\ctikzset{voltage shift = 2}
\circuit

\end{document}