Codec name normalization breaks custom codecs

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2021-07-23.10:18:59.285>
labels = ['type-bug', '3.9', 'expert-unicode']
title = 'Codec name normalization breaks custom codecs'
updated_at = <Date 2022-01-25.02:02:30.022>
user = 'https://github.com/bodograumann'

bugs.python.org fields:

activity = <Date 2022-01-25.02:02:30.022>
actor = 'methane'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Unicode']
creation = <Date 2021-07-23.10:18:59.285>
creator = 'bodograumann'
dependencies = []
files = []
hgrepos = []
issue_num = 44723
keywords = []
message_count = 1.0
messages = ['398042']
nosy_count = 5.0
nosy_names = ['gregory.p.smith', 'vstinner', 'ezio.melotti', 'methane', 'bodograumann']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue44723'
versions = ['Python 3.9']