this belongs to an issue reported in following micropython forum thread.

https://forum.micropython.org/viewtopic.php?f=15&t=9103

the asyncio Loop close() method currently does not perform any action.
whereas the new_event_loop() method implements the functionality.

in CPython its documented as
https://docs.python.org/3/library/asyncio-eventloop.html#asyncio.loop.close

performing the same functionality in close() would resolve this behaviour,
and would make uasyncio more compatible to CPython.