Stop / prevent WordPress from updating permalinks of custom post type

I fixed the issue. Something wrong with functions.php was changing the permalinks and creating this issue. Rolling back to a previous version of functions.php solved the problem. Infact, I didn’t have to do anything other than replace that file and all the links appeared correctly again.

I then went through and redid all the changes I’d recently made to the functions file one by one and didn’t encounter the issue. I may have accidentally deleted something or added something to functions.php by accident.