I agree, strongly. [ and ] are perfectly valid characters in a subject
line and can be used for all sorts of reasons. The fact that they are
also used to enclose the group name is irrelevant. I would also say
that the use of # for things other than hashtags is also perfectly
valid - and in itself causes much confusion when an innocent # is
picked up and a 'new hashtag' is created. We do not use hashtags in our
lists.

Dave

On 7 Feb 2021 at 7:31, Malcolm Austen wrote:

I see no bug here. In my experience, it's normal list practice to simply
prefix the subject if the list prefix text is not already present.
Banning other square brackets would, for example, prevent someone asking
in a techie groups about the use of [a-z] in a regular expression.

Malcolm.

http://davesergeant.com