man in the middle – How Data Link layer trailer prevents data from being intercepted and tampers

I am reading on https://tryhackme.com/room/introtonetworking, it is talking about OSI model.

It said that Data Link layer trailer can increase security as the data can’t be intercepted and tampered. How can it do it?. If it is because of the trailer added in at the end of the data, what stops a man-in-the-middle from changing this trailer too?

The data link layer also adds a piece on at the end of the
transmission, which is used to verify that the data has not been
corrupted on transmission; this also has the added bonus of increased
security, as the data can’t be intercepted and tampered with without
breaking the trailer. This whole process is referred to as
encapsulation; the process by which data can be sent from one computer
to another.