UTF-8 error when importing pyplot pdf into overleaf latex

I am implementing a plot using pyplot and saving in pdf. When I include the pdf plot in latex I get error

String contains an invalid utf-8 sequence.

I am using LuLatex on overleaf to compile.
Here is the pyplot code: https://gist.github.com/proywm/49be64968550ae683b34be6fbb517daf

I am including the figure as follows:

begin{figure}[t]
centering
input{figures/eval/Accuracy_Spec_go_H1.pdf}
caption{Accuracy} label{fig:split_train_stitch}
vspace{-0.2 cm}
end{figure}

What should I do to resolve the issue?