The robot voices kill me (make one yourself you lazy assholes), but the speech overlay was actually originally done to make the platform more accessible to the deaf, which Is basically just them outsourcing subtitles to the users, but it's a pretty widely followed social phenomenon, unclear if it's user driven or not, but commenters (unclear if bots or not) will spam popular videos without them asking them to add them to followup videos, and other creators will do 'call outs', it's to the point where even most conservative TikTok people use them.