I understand your feelings. I had a very interesting project at my FAANG start, it was fun, required creative and learning new things.

With time I got assigned stuff that wasn’t challenging, and that hit me hard. And also locked in legacy code or big-Corp only way of doing things.

But you have to remember that you have a very good job. Most people would like to work there someday, and it opens many doors.

It’s yours to decide, but I would bet in an internal transfer. If nothing is interesting, starting exploring other options. But big Corp is always like this. The only difference is if you are lucky with your manager and/or project