The thing with Topre RGB is that it's not uniform circle, there is an indent at bottom due to how the housing is constructed. So you need the RGB edition ring.
https://deskeys.io/products/des-topre-silencing-rings-rgb-editionSo chances are it might've been using the wrong rings for so long so it keeps the dome somewhat compressed and it's now worn into shape. I think if you remove all silence ring for a while it will come back a bit but probably not come back to its original state.
My wife had a FC660C that I used to use thicker silence ring in it, then after I remove it I still find it not as tactile as I remembered. So as you said maybe prolonged period of compression deformed the domes a little bit. I have since removed all silence ring and they do come back a bit but maybe not to its original state.
Though Topre in general, the most you use it the softer it gets, so you'll never get that "new dome" tactility unfortunately.
I'm using 55g R2, I find even in the morning the dome is stiffer and as I use it through the day, the dome are softer at night lol.