Bachelor in Paradise - Speaking before the Island

The last full paradise I watched was the one where Joe and Serena got engaged. That season was the one with the drama about people making plans in advance to be together as a couple on the island.

I'm sure a lot of contestants talk to each other via DM or at events without knowing whether or not they will be cast. What is the rule now about speaking with each other, particularly once you know you have been or are likely to be cast?