New File Sharing Experience in Teams
When users share a file by browsing to it in OneDrive or Microsoft Teams and Channels, all recipients are granted access along with the default permission that's set at the organization level.
When a user copies and pastes a sharing link, the permissions set on that sharing link are honored and the SharePoint URL is shortened to the file name. In other words, Teams uses just the file name to link to a file.
When users share a file from within Teams, they can set who can access the file just like they do across Microsoft 365. They can give access to anyone, people in your organization, people with existing access, or specific people (which can include the people in a 1:1 chat, group chat, or channel). When a file is shared, the file preview is available in the message, along with all file actions such as Open online, Download, and Copy link. By default, the file opens in Teams. Sometimes, the sharing link may not have converted to a file preview by the time a user sends the message. The file preview will be generated by the system, but in this scenario, the sharing link won't be shortened to only the file name.
When users share a file in a chat or channel, they're notified whether some or all recipients don't have permission to view the file. They can change the permissions on the file before they share it by clicking the arrow next to the file preview that now appears in the message.