In Polish you can type "A, to dobrze" (en: Oh, that's good). But Teams change "A," into "A." point. This just looks bad and is not grammatically correct.
I think this was added this year. I cannot find any settings that would disable this :unamused_face:... And I don't think it is really need. How many times you actually need to use letters in points. I never do in chats. Bullet points and numeric points are enough even for technical conversations.
AFAIK, there is no way to disable this (there is in other M365 programs). You might want to contact answers.microsoft.com tech support site, where authorized Microsoft agents are available to troubleshoot a variety of issues until resolution.