I was not formally notified that these packages have been adopted into extra
PMs should delete the package from AUR after adoption -
https://wiki.archlinux.org/title/Package_Maintainer_guidelines#Moving_packages_from_the_AUR_to_extra
Deleting the package notifies you about it(iirc).
Lack of credit is due to your work not being used, and a Thank You
message, which I agree is a nice thing to do, is not required.
It SHOULD be required to check AUR for a naming conflict if you make a
package in extra, and whether you are using the existing PKGBUILD or
rolling your own is immaterial.
Contacting the maintainer of the AUR package is the bare minimum, and if
it is not in the guidelines, it should be added.
We are all grownups here, and we should show some respect for each other.
Best,
Evert