How to tell if a file system has been shrunk? Is there any way to tell if a file system (regardless of its type) has been resized? Specifically shrunk?

As far as I know, there is no direct way for this purpose.

The only idea which sprang to my mind was to check out and examine the contents - e.g. filesystem - metadata of the partition. If the size recorded in metadata does not match the size of the partition, it may have been resized.

Even if the contents has been resized too, some metadata may not have been updated to reflect the new size. For instance, the number of inodes in an ext2/3/4 filesystem is fixed at the creation and does not change when the filesystem gets resized. So being aware of concepts and rules is needed. So assuming the filesystem was created with the default values you can compare the output of `e2mkfs` in sumulation mode and the output of `tune2fs -l`.