Sounds like collusion through a third party. Similar to the landlords all signing up to the same pricing service.

Same play as the meat industry leveraging "data analytics" to fix and sort at https://www.agristats.com/.

[1]https://www.justice.gov/archives/opa/pr/four-states-join-jus...

[2]https://farmaction.us/2023/10/12/food-price-fixing-is-still-...