As per the title, previously, swamps used to only connect to one piece of land, and wouldn't attach itself to 2 or 3 other biomes. However, current world gen allows swamps to connect to several other pieces of land. It seems to really like to connect to the Dfly desert, as seen from a few worlds I've generated, though the two may or may not be independent of each other.
Steps to Reproduce
Generate world. Explore world. See that swamps are now connected to multiple biomes.
This issue has not been confirmed by a developer yet.