Introduced June 20, 2017
Hints: The 25 Gb/s ports can use optical SFP28s, so this can't be Gen 1 Tomahawk. It has 22 MByte of buffer which matches Tomahawk+ but not Cavium or Barefoot. So, probably Tomahawk+.
There is a data sheet, but it isn't terribly helpful. Much better is the switch product guide that has info on data buffering.
Lenovo added a new part by appending the letter "O" to the number, so NE2572O. The "O" stands for ONIE which distinguishes from the original model that ran software named Cloud Network Operating System (CNOS).