The purpose of this custom bibtex stlye plainyr-rev.bst is to instruct BibTeX to use reverse chronological sorting for references, which is typically used in academic CVs. Since the development of this BST style, the LaTeX world has move forward and today, I personally consider BibTeX as outdated and suggest to replace it with BibLaTeX, which is much more powerful, customizable, and easier to use than good ol' BibTeX. Also, BibLaTeX supports reverse chronological sorting just out of the box.

Hence, I recommend that you replace your use of plainyr-rev.bst with the modern BibLaTeX alternative. I have created a small sample modern-alternative.tex to get you started.

Christian Plessl, December 2021