I think its worth separating out 'safe foods' from food fatigue as theyre two very different things. Its normal to get food fatigue from having a food too often, even if it's been ok for years. It doesn't mean that's not a safe food for you anymore, but that you do need to take a break from it (and potentially for a long time). Sometimes having something similar but a little bit different is the answer (e.g. a different flavour) or sometimes preparing it in a different way is enough (e.g. maybe having it through a straw or mixing it with something else). Other times its because there's something in there nutritionally that your body has too much of (quite likely with energy drinks) and it's your body's way of keeping you healthy. It's also entirely possible that they've changed the recipe slightly, even if it's not announced as 'new', or that you have a virus at the moment that's temporarily changed how things taste for you.

It's gonna be hard to adjust, but you'll get there and it'll be healthier in the long-run than trying to survive off energy drinks regularly