Trying to ascertain the true Gain Bandwidth Product on this device - the closest the data sheet comes to that seems to be on page 21 talking about transimpedance design - there does not appear to be a number given there or anywhere - and no, the min gain times SSBW is not the GBP normally.
Actually, I did find it in Figure 18 where looking at the 40dB 12.4Mhz will give about a 1.24GHz GBP, if that is not right, let me know - but I think i am done now.
I'd estimate the GBW of ADA4895 to be a little higher than your calculation based on the same Figure 18 you noted.
At 40dB gain, the frequency reads more like 22MHz or about 2.2GHz GBW.
At 50dB (316 V/V) gain, the frequency reads 10MHz --> GBW = 3.16GHz GBW.