\documentclass{scrartcl}
\usepackage[ngerman]{babel}
\usepackage[most]{tcolorbox}
\usepackage{xsim}
\usepackage{tikz}
\DeclareExerciseProperty{punkte}
\DeclareExercisePropertyAlias{punkte}{points}
\DeclareExerciseEnvironmentTemplate{klausuraufgabe}{%
\tcolorbox[standard jigsaw,
opacityback=0,
opacityframe=0,
coltitle=black,
breakable ,
drop shadow ,
beforeafter skip = .5\baselineskip ,
title =
\textbf{\GetExerciseName~\GetExerciseProperty{counter}}%
\GetExercisePropertyT{subtitle}{ \textit{\PropertyValue}}%
\IfInsideSolutionF{%
\GetExercisePropertyT{points}{ ($\GetExerciseProperty{punkte} = \text{\points{\PropertyValue}}$)}%
}%
]%
}{\endtcolorbox}
\DeclareExerciseType{klausuraufgabe}{
exercise-env = aufgabe ,
solution-env = loesung ,
exercise-name = Aufgabe ,
solution-name = Lösung ,
exercise-template = klausuraufgabe ,
solution-template = klausuraufgabe
}
\DeclareExerciseTableTemplate{punktetabelle}{%
\renewcommand*\arraystretch{2}
\XSIMputright\ExerciseTableCode{ \hline Aufgabe & }
\ForEachUsedExerciseByType{\XSIMputright\ExerciseTableCode{#3&}}
\XSIMputright\ExerciseTableCode{
\LARGE$\sum$ \\