2 days ago I've changed the Internet plan from 400Mbit to 1Gbit but according speedtest download speed did not change at all

I'm connected to Netgear CAX80 (up to 2.36Gbit rated) using Ethernet (Cat 5E) cable directly from my PC (2.5Gbit network adapter).

Was expecting at least SOME improvement but nah. It appears Comcast did not recognize change of the plan.