\DeclareGraphicsExtensions{.pdf,.png,.jpg} adds a not needed limitation #7
Description
In line 83 of NotesTeXV3.sty you have
\DeclareGraphicsExtensions{.pdf,.png,.jpg}This is a not needed limitation for the supported graphics file extensions and formats. Usually usage of a \DeclareGraphicsExtensions is neither needed nor recommended. The backend driver knows better, which extensions it supports.
For example, if someone uses PDFLaTeX, your declaration would remove .mps, .jpeg, .jbig2, .jb2 but also all upper case extensions: .PDF, .PNG , .JPG, .JPEG , .JBIG2, .JB2 from the list of supported extensions. So, e.g., Linux users would need to rename a file like TEST.PDF to TEST.pdf before it can be used.
Usage of your package with LaTeX → DVI → PDF is also not possible with this declaration, because dvips.def and dvipdf.def (the relevant backend drivers for this scenario) do not support any of the extensions you are declaring.
Removing the line would not break any existing document, because the order of extensions with PDFLaTeX (or LuaLaTeX) is already the same. But it would support more file types and also upper case file names.