> I am worried about burning bridges

If you’re working with good people, leaving a job on good terms shouldn’t result in burnt bridges. Especially if you’ve been voicing your concerns and nothing has changed. I know I’m welcome back at any place I’ve ever worked - every time I’ve left for a better / more suitable role or to take time off (I’m currently taking a few years off due to burnout), my managers / bosses have been very supportive.

> Am I right in preparing to leave rather than to try to fight my way into the positions I want?

Absolutely. In fact this is expected. It’s usually faster to grow your career horizontally opposed to vertically.