Connecting Teams calendars with external services like Outlook for unified scheduling
Hello, my name is Jude.
I'll be glad to proffer solution/clarification on this issue.
I understand your concern to restrict team members from editing their time but that feature isn't readily available now on teams, all teams member are automatically able to make changes to calendar as long as their part of the team.
I'll advise you suggest this feature to be added to Teams as I'm sure this will be a good addition to future teams users also, please follow the step below to suggest a feature.
From the teams app, click on Help then choose suggest a feature and suggest feature.
Kindly get back to me if you're in need of further assistance.
Thank you.