There is a one year cool down period.
The test checks whether you have the skills and performance of a senior python backend developer and as you say, at the time of taking it, you didn't have the required proficiency.
You can apply 365 days after your last application, though please note that you have to be better than the last time.
I have around 5y of Python experience (11 of career), but haven't touched it in the last 2y, so I'm a bit rusty.