Is it permissible to supplicate with the following formula: "O Allah, all praise and thanks be to You, as You have been praised and thanked by all those accepted, and as they praise and thank, and as they will praise and thank forever and ever, O Most Generous"?

There is no harm in praising Allah and glorifying Him with these beautiful words, as long as they do not contain any reprehensible or forbidden meaning, or violate the Sharia. However, adhering to what has been authentically reported from the Prophet, peace and blessings be upon him, is more perfect and superior.