Why would that be unforunate? If you installed in 2019 - you 100% got the pacnew file for the “new yay” as you call it. You have had it this whole time - it was automatically updated when you updated (assuming you update). It was up to you to implement it - That’s how Arch/Endeavour work. If you want things to be “automatic” in some way - this may not be the best distro for you.
It is assumed if you want something new, you will install it. It is assumed if you get pacnew files you will tend them, and it is assumed you will keep your computer up to date the way you want it to be.
If you update your computer you will always have the most recent available version of every package. There’s no such thing as an “old installation.” You can only have installations that need to be updated. Endeavour always just is.
If you did delete the pacnew file - you can always get the most current default EOS pacman.conf file here: