Neither the head of state, nor the president of government, nor even the minister of Foreign Affairs were present at the inauguration ceremony of Claudia Sheinbaum as the new president of Mexico, which took place on October 1.
I assume that the reader is aware of the controversy sparked by sending the invitation to the President of the Spanish Government and not to King Felipe VI. Anyway, I recommend that you read the article by Emeritus Professor of Philosophy of Law of the Pablo de Olavide University in Public“Should Spain apologize to Mexico? Responses and negative responses. This is the best analysis I have read. I have nothing to add to what he says.