Because no Package Maintainer wants to maintain it, is my guess.
Arch Linux
The beloved lightweight distro
I thought it is already maintained? And it's popular enough to have someone who would do it?
AUR package maintainers are not the same as Arch repo package maintainers. Anyone can be an AUR package maintainer.
And it is not straightforward to become arch maintainer. There has to be a level of trust in that person. The team shouldn’t be too big to manage. And there are other considerations too.
Because it's a two-part ting. Being popular enough and finding a maintainer (from them limited pool of official maintainers there are) who does it.
The AUR is unofficial and no one cares much if updates are delayed there but the offcial repositiories have higher standards and -and that's related to the list of browsers also not in the official repos- maintaining google-based browsers is a pain in the ass (in fact I'm used to seeing warnings because librewolf is once again flagged aus out-of-date but the AUR maintainer didn't have the time to fix the latest build yet).