Two Office 365 Message Center notifications bring news about an increase in the number of participants for a Teams group chat to 100 and improvements in shareable links for files. Moving the limit from 50 to 100 for a group chat makes these conversations more flexible. Adding permissions to the sharing links used by Teams gives users more control over how they share information with others.
https://office365itpros.com/2019/05/14/teams-increases-group-chat-limit-improves-shareable-links/