If you find your teams in Office 365 are regularly sharing files across different MS-Teams, then you may wish to create a shared library with either full editorial or read-only permissions.

1. Open the relevant SharePoint site in SharePoint,
2. Click home and create a new library,
3. Create a folder and click manage access,
4. Grant access to relevant teams or people,
5. Set permissions,
6. To create a short cut to the library in the MS-Teams file tab, click to add cloud storage,
7. Select the new library,
8. Repeat steps 6 and 7 to create the shortcut link in other teams libraries.

Please note, if people are regularly collaborating across teams it might be worth reviewing how Teams in MS-Teams are structured.

The Teams environment should support how your people work. Optimal results are usually achieved with stable teams and channels. When structuring your Teams environment consider who you wish people to collaborate with most closely, the type of work the team undertakes, and other groups with which they may need to coordinate.

For further information consider this article:

Building a high performance environment with MS-Teams