On the 20w48a version of Carpet when using it on a server everyone gets permissions to /draw command. I tried without Carpet and non-OPs lost their access to /draw.

The /draw command is from carpet itself, and by default it is available to everyone, so if you remove Carpet, nobody has access to /draw (it doesnt exist)
You can change that with /carpet commandDraw ops to enable that command only for OP's
However this will likely change with #582 to be only available to ops by default

yes, there is #582 that was almost unanimously agreed on in favour of keeping the previous behaviours. Essentially duplicates #582