Currently only seen in an old-style generation world. There are certain parts of the land ("shoreline" in most cases) that are not possible to jump onto from the water, even if the water is shallow and should allow you to hop onto the land, like how it has been in the past.
Image 01 shows that I was able to reach the land by hopping out of the water. The water is shallow (1 tile deep).
Image 02 shows that I was unable to reach the land, and am stuck futilely hopping out of the water in an attempt to get onto the land. Even with artificially-shallow water (one block placed to change 2-block deep water into 1-block deep), it is impossible to get onto this land without moving from elsewhere on the land or using a boat.

I have witnessed this in small parts of other landmasses on the same world, and also on a natural 1-block island and an artificial island expanding from that island. I am not sure if there is a new water mechanic that makes it impossible to jump onto certain shorelines.