Article 2, Section 1, Clause 7 of the United States Constitution says:
“The President shall, at stated Times, receive for hisServices, a Compensation which shall neither beencreased nor diminished during the Period for which heshall have been elected, and he shall not receive withinthat Period any other Emolument from the UnitedStates, or any of them.”
An emolument is any kind of payment.
The Trump government has decided that the next G7 summit will be at a Trump owned and Trump managed resort in Florida. The US government is now going to pay 10's of millions of dollars to Donald trump's business. A business which Trump has not divested from. This means Trump directed the US government to pay him 10's of millions of dollars.
This is a very clear breach of the constitution and therefore a breach of his oath of office. This is yet another impeachable offense.