That is a good question, Julie. It made me really think about the vase. Sommerso is something I usually stay away from. The thing that made me favor a more recent piece is that there are so many vases that are made that look like this. Several companies make them. Red with yellow are common colors. So in the absence of anything, such as clear lines between layers, that definitely points to Poli, it is more accurate to leave the attribution at simply Murano. eBay has had a bad effect on the name Poli. Any layered sommerso object is attributed to him on eBay.
There is one thing distinctive about the vase discussed in this thread. The outer glass is blue instead of clear. I did not really note that until I checked back. I hope there is a layered sommerso person reading who has some ideas on who made these vases with blue glass.