remove live usb while running from it

Why are you running from it? There's no need to be scared, it doesn't normally bite

A lot of live images will run entirely from RAM, flash drives are typically quit slow so it makes the experience much nicer.

It's creating a RAM drive and just keeps working from there. You can even plug the stick back in and save files on it, if needed.

That's because at booting time this live USB is loaded into your RAM and it is safe to remove it once you complete the boot process.

The main reason to "eject" flash memory is if it is in the middle of a write operation because they are rather long due to how entire pages must be erased and rewritten. Depending on how this write process is managed and how the hardware is constructed it can cause corruption from removing something the wrong way.

I'm not sure about how the larger distros work, but with something like OpenWRT, everything is running in RAM. I'm pretty sure that is how Live USB always works.

I'm pretty sure even the distros that can run from USB with persistence are running an immutable OS that runs from RAM and then using an extra partition on the USB drive for persistent storage. The immutable nature hints that it is likely running in RAM.

Liveusb sistems do get stored in RAM since it's so much faster and reliable. Also I'm pretty sure most liveusb are read-only so it's Hardee to modify data. Manjaro must be loading small parts into Ram, or you didn't had enough ram, so when you took it out it only had the data on RAM which wasn't enough for it to process any command

Its only fine if you use the toram kernel parameter (some distros ignore it)

Yep, I've done that. Just hard power off and I would recommend reformatting the drive. You can usually still get your files back by mounting it on a functional computer.

I was going to ask if you'd tied a string to it, but now I understand.