Inspecting the code behind donate.python.org I noticed that Stripe is being used, with stripe fingerprinting the user and setting a persistent cookie (for a year).
Such tracking may not be compatible with the PSF privacy notice which does not include Stripe as a third party service - nor does it mention anything about tracking cookies. Some cookies are attached to all requests to donate.python.org - so you are the controller in this case (as far as I understand).
The stripe cookie is also sent when I make a request to python.org (also there seem to be Google Analytics cookies there? I haven’t figured out where they come form - but there shouldn’t be any per your privacy policy). Maybe these date from before your switch to Plausible?