When you are in a dimension, the inf is automatically reset and you lose most of your progress. You have risen enough on your ring to move on to the next level.
I see now after having it happen a few times, but the reset doesn't appear to work properly since it doesn't reset my current level and I appear to be keeping my ascension points and mutagens on the reset. It didn't make a huge difference until my 3rd reset where I gained the ability to get multiple rebirth tiers at once. Since my level didn't reset, I was able to get rebirth T35 immediately.