I recently spoke with support about closed captioning for GTW sessions. I was directed to this community post that discusses transcripts. Unfortunately, transcripts are not a solution because it is a question of access and inclusivity for the hearing impaired.
Firstly, people that are hearing-impaired need the ability to participate at the same time as all participants. Secondly, reading a transcript means that you're not able to view the slides at the same time which means a lot of context is lost.
Closed captioning is critical for all people to participate in a webinar!