A drive can plug into two computers without behaving the same way on both. Before entrusting it with a weekend’s photos, check a more useful question than “Does it appear?”: can each computer save a file and read back what the other wrote?
The connector is only the first check
USB-C describes the connection, not the drive’s file system. For ordinary file exchange between Mac and Windows, exFAT is a common option supported by both. Apple lists it among its Windows-compatible formats; Microsoft documents it as a supported Windows format.
That does not make it the right choice for every job. If this drive is meant for a particular backup application, television or camera, check that product’s requirements too. A disk used to pass documents between laptops has a different job from a dedicated backup destination.
Try the existing drive before changing it
Choose a disposable test folder with one document and one photograph. Copy it from the Mac, eject the drive normally and open both files on Windows. Save a second test file from Windows and read it on the Mac. Keep the original test files on the computers throughout.
If one step fails, record the exact error. Check the current format and available space before concluding that the whole drive needs replacing. A failed write and an unreadable file are different observations and deserve separate notes.
Formatting comes after a verified copy
Formatting erases the selected volume’s contents. Even a quick format is not a way to preserve the existing files. Before any change, copy what matters elsewhere and open that copy. Check the selected device’s name and capacity; disconnect unrelated external drives if that makes identification easier.
After preparing an empty drive, repeat the two-computer test before moving important work. Treat successful transfer as a compatibility check. It does not create a second backup if you then delete the only other copy.