My wife and I haven't had any issues with it, they're just easy to paint as the bad distro because it's supposed to uncomplicate Arch for your average user, but has had some certs fall through the cracks and they had kind of an asshole response to address it (thank God Gnome and Linux devs are never contentious folks), and apparently people don't read the warnings about enabling AUR in the package manager. Don't get me wrong, it's not the perfect distro, but it doesn't deserve nearly as much hate as it gets. It's not Canonical, pushing Amazon and telemetry by default 😆 besides, it's got some cool features out of the box like one of the better default dualboot grubs I've seen by default, the ability to have multiple kernels installed simultaneously from multiple streams, and while it's common anymore, was one of the early adopters of providing Nvidia drivers on install. Lots of people have strong opinions on what distro is best, and Manjaro manages to be an easy one to point fingers at.

Manjaro piggybacks off of Arch and some Arch users want to be obnoxious about it.

There's nothing wrong with the distro, itself.

The maintainers have done some inconsequential noob-ish things with the site's website, and the in-house package manager (pamac) had a bug that took down the AUR once and Arch users that couldn't host their own website if they wanted to like to point fingers and troll.

here

Mostly the admins. They've forgotten to renew their SSL certs multiple times, causing various issues, and they introduced a bug that briefly DDOSed the entire AUR.

The distro itself seems fine. Although, I don't see why you wouldn't just use Arch with Archinstall or EndeavorOS if you really want that GUI installer. Both are much better managed imo.

This is often linked. It's basically just bad management, bad tools and much worse it is holding back security updates.