I am having the same issues with Wifi. I was so excited to get going with it, and upon the very first boot running the latest Manjaro ARM everything was nice, dual 4k monitors started up right away, AirPods and SteelSeries Nimbus Gamepad Connected via bluetooth immediately.
But then the first thing I did after that was go to update the distro, and was getting Only 100-500 KB/s down when updating the OS. It was a real let down. I can’t even load a Google Sheet properly with these wifi speeds. Ethernet not really an option where I am in the house. My iManjaro and ManjaroBook Pro are getting excellent throughput right next to the Pi 4.
Hopefully once the updates finally get done it will be better, but as it is now it is not going to be usable as a workstation (Email, Google Business Suite, Stream Music, and Retro Emulation Gaming is all it is going to have to do well)
But since this seems to be such a common problem (threads popping up everywhere) I would think we aould all benefit from a reason why the performance is so low. Do we need to update firmware out of the box immediately? I will try that as a next step.