Your complaints are something that comes up regularly since at least the end of Heavensward. Yoshida& the team talked about it a few times, but the reason the game is so formulaic is because it allows for people to come in and come out of the game whenever they feel like it and know what they go into when they come back, basically.

On another note, the game is so formulaic because... it's the game. That's FFXIV. They're not gonna dramatically change the formula. Yes maybe we could wait 3 more months before an expansion comes out (which is not a smart business decision tho), but you'll just get the content of what would have been the next patch into the normal release. Which amounts to the same. And while a dramatic/substantial change in formula would probably appeal to you, to a lot of people it would probably be gratting, especially if the change goes in a direction that is not to their liking. The current formula has at least the merit to speak to most types of player populations. (And to be fair, MMO players always want change, then invariably complain about change).

Lastly, expansion launches are always a bit low on endgame content, by nature. It gives the player time to level up a bit of everything and go on to a few things before bigger things like your Bozjas and all come out (which was what Endwalker lacked). If the formula feels stale, or the current content is getting boring on repeat for you, frankly, do not hesitate to stop for a time and go play another game. It's not a jab to you, different games are there for different experiences. And XIV will always be there to come back to when you're not bored with it.

EDIT : also you played 6000 hours in the last 4-5 years. Burning out of it is kinda natural.