Initially, there was USB 3.0 at 5Gbps, USB 2.0 at 480Mbps, and USB 1.1 at 12 Mbps.
Then, when they added a 10Gbps mode, they called it USB 3.1 Gen 2, and renamed USB 3.0 to USB 3.1 Gen 1.
They already have plans for USB 3.2: 5Gbps will be USB 3.2 Gen 1, 10Gbps will be USB 3.2 Gen 2, and 20 Gbps will be USB 3.2 Gen 2x2. Yup, Gen 2x2 is next.
And there is no more USB 3.0 - presumably no vendor wants to have to sell an older number, so they rename them all so consumers are confused and think they are all the latest 3.x
ref: https://arstechnica.com/gadgets/2019/02/usb-3-2-is-going-to-...
As soon as its phones go USB-C, they're going to have to deal with half a million people on the internet complaining that their junk shop cable doesn't work right or do what they thought it would.
And the latter two would be "USB 3.3", "USB 3.4", problem solved :)