I didn’t know about all these different AUR helpers written in different languages. Thanks to the discovery article I stumbled on this arch wiki link:
https://wiki.archlinux.org/title/AUR_helpers#Comparison_tables
A short description maybe interesting but would probably warn newbie to rather use yay since it’s in the eos repo and probably easier to troubleshoot.
Yes sir, I actually use yay -S for downloading AURs.
But, I was in urgent need to download LaTeX and ffmpeg, that’s why I used other one.
You can download packages from arch repository either via yay or pacman. However you cannot download AUR packages via pacman because AUR is not equal arch repo. Just to clarify.
Latex and ffmpeg are available in arch repo.
Search arch repo
https://archlinux.org/packages/staging/x86_64/ffmpeg/
Search AUR
I generally use pacman anyways because I have very few AUR packages myself. Only use yay to update every week or so my AUR package.
Thank you sir for providing crisp and clear information regarding this. As I am newcomer to Linux world, hence , little-little informative inputs from experienced users like you will help me in my journey here.
No worries, just making sure you know the difference as I cannot estimate arch know how of new forum users. 
My knowledge is very basic but try helping if I can. Although I installed arch a couple of time previously but still lots to learn, specially terminal commands out of my comfort zone.
But this is a super community to learn a lot in no time.
yay just got updated to v11.1.1 to address the recent issue as well as a few other issues. Let’s go! 
Yay 11.1.1-1 is released to EndeavourOS mirrors. Will come near you soon.
well, looks like something is moving again there (by the comments posted in the linked topic during the last 24 hours with a new maintainer probably arising) - but yeah, the situation looks bad.
If you can’t build some packages(matrix-mirage for me) after applying the patch mentioned above with AUR is unavailable at this moment error, Uninstalling and reinstalling with pacman will fix it.
there is no issue anymore since yesterday already… it was already fixed in between 24 hours after issue comes up 
And now yay AUR is working like before… and will also after AURWEB updates to only allow the one URL that was causing the issue for YAY before…
But if you applied the “hack” with the sed command before it is a good idea to reinstall yay … but as it is also updated today you will have it replaced already…
No issue with the AUR and no issue with YAY all solved …
–closing–