[mjf]

Edit:

Scratch the previous comment. Thought I was looking at the difference at the lower point where the taper started.

Could potentially be risky, but also nothing.

My concern is that you've had multiple lower bearings going indicating that there's play in the fork even assuming there's appropriate preload. There's also a gap at the top of the steerer/plug, meaning that's either started to pull out of the steerer, or the steerer isn't cut flush. Not world ending, but would explain some of the play that's developed in the headset.

Because the compression in the carbon has developed at the bearing contact point, you're going to have a minimal, but likely perceivable point of play over time, and is likely contributing to your lower bearing wearing out. I'm doubtful of anything catastrophic happening, but your maintenance costs being higher than they should.

For peace of mind, I'd try and replace the fork.