This would be quite an accelerated timeline if Apple ships its second-generation M-series chip only eight months after the first. Typically, they’ve followed a sort of six-month tick-tock pattern for the A-series, launching a new major revision in the fall with the new iPhone, and launching an “X” revision in the spring with new iPads. I think most observers have been expecting an “M1X” for Apple's first pro-oriented…
M2 is probably based on the Arm v9 ISA and has been in design for years.