Been trying to run through possible ways to discourage use of data center travel or encourage remaining on a home data center. I keep coming up with how they either can be countered or would hinder the intent of data center travel.

The only thing I can think of would feel harsh to players and generate very strong pushback - debuff Traveler attributes.

Friends trying to play with actual friends probably wouldn't mind that the traveling friend has had their attributes debuffed by 2-3% (or whatever amount) - they just want to play with their friend. But how many would tolerate it in PF filled with random players, with potentially multiple (or even all of them) having the debuff?

Those who want to be part of a specific raid static will feel forced to change home worlds but then they would still have the option of using data center travel to play with friends on their old home world. The debuff would only affect Travelers and not Wanderers so needed transfers wouldn't be blocked by the Congested world status unless all worlds on a data center are Congested.

It's an ugly solution but I can't think of something better that would allow data center travel to remain as is while getting players to prioritize play on their home data centers and only using data center travel to play with friends/do more casual content or as a last resort during offpeak hours to find parties.