The Ultra Boost 2019 actually feels better than the older Ultras. I thought I was falling into some form of recency bias but I wore all my UB's back to back and you could really feel it.
The sole has better bounce to it. I hesitate to use the word firm as it does feel like there's more support but it doesn't feel harder than the older UB's.
I suggest you wear your UB's to an Adidas shop, try the Ultra '19s, and see for yourself.