I've been writing python for 20 years, and I truly cannot think of an instance where pasting code was an issue. I use vim mostly without any plugins, not any fancy editor.
I've only used python a few years professionally, but seen it multiple times. With other languages I paste in code between some brackets, run the autoformatter and it looks as I want. With python I paste in some code, run the autoformatter, only to see because of spacing issues half the lines I pasted didn't get properly parsed to be inside the for loop or whatever.
Also makes it hard to copy a snippet to run inside a REPL or whatever.
In general just a huge amount of pain, and the "good thing" about how it forces well formatted code I've never seen as an issue with autoformatters and linters in othet languages.
The "trick" is to copy and paste on the right block level. Just set the cursor appropriately (which the editor does for you if you use the feature to jump to block start or end).
Than everything just works.
(For that to work even better the stupid feature of some editors to remove white space form all empty lines should be disabled. So pressing enter or going to the next empty line will always position the cursor on the correct indentation level. Than it's easy to paste code blocks everywhere as even empty lines are correctly indented).
I've written a lot of python in my life (but most of the time not as my main day-to-day language) so whenever I had to try something small in a REPL I do paste. I guess it would work to highlight a piece of code and run it externally with a shortcut, but I've never set that up, so I did indeed run into this problem more often whenever I was just taking up Python again (for example I find [x for x in ....] kinda horrible and have at times fat-fingered if it's twice nested)
Also makes it hard to copy a snippet to run inside a REPL or whatever.
In general just a huge amount of pain, and the "good thing" about how it forces well formatted code I've never seen as an issue with autoformatters and linters in othet languages.