The GP host countries have to pay the expenses for travel, meals and lodging - relevant excerpt from the 2021 Skate America competition announcement:
4. MEALS, LODGING and TRAVEL EXPENSES
4.1 Meals and Lodging
The organizer will provide and cover the expenses for rooms and meals for all Competitors and Judges participating, beginning with dinner from Wednesday, October 20, 2021 until breakfast on Monday, October 25, 2021.
....
The organizer will provide and cover the expenses for rooms and meals also for the ISU Representative, the Referees, the Technical Controllers, the Technical Specialists, the ISU Grand Prix Coordinator for the ISU Grand Prix of Figure Skating, the Data and Replay Operators during the same period as indicated for the competitors.
4.2 Travel Expenses
The Organizing Member will pay air travel expenses based on the best available economy airfare rate for all competitors invited to its ISU Grand Prix of Figure Skating event, for all Judges invited, from their domicile to Las Vegas, NV and return. If the competitors or judges decide to arrive earlier or stay later than the approved dates listed above any cost difference will be the responsibility of the competitor and/or judge or their respective federation. If competitors or judges desire to upgrade using miles or fly on a desired airline, the Organizing Committee will review with the understanding that the competitor and/or judge is responsible for the difference in price from the best available economy airfare available. The air travel expenses of the Referees, Technical Controllers, Technical Specialists and the Data & Replay Operators are covered by the ISU.