Reference cycles from a WeakKeyDictionary value to its key aren’t collected

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2021-07-19.21:23:17.423>
labels = ['library', '3.9', 'performance']
title = 'Reference cycles from a WeakKeyDictionary value to its key aren\xe2\x80\x99t collected'
updated_at = <Date 2021-07-19.23:06:04.944>
user = 'https://github.com/andersk'

bugs.python.org fields:

activity = <Date 2021-07-19.23:06:04.944>
actor = 'andersk'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2021-07-19.21:23:17.423>
creator = 'andersk'
dependencies = []
files = []
hgrepos = []
issue_num = 44680
keywords = []
message_count = 2.0
messages = ['397841', '397845']
nosy_count = 1.0
nosy_names = ['andersk']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'resource usage'
url = 'https://bugs.python.org/issue44680'
versions = ['Python 3.9']