Looking at the graph I would put you around 165. I would say that in general the AeT test for a fairly well trained athlete shouldnt feel that “tough” at all but that’s a subjective thing. As you mention here correctly those with more developed aerobic systems and a relatively small Z3 are working “harder” at the top of Z2 than someone whose aerobic system is more deficient. This can certainly affect how hard it feels. If you spent the vast majority of your winter training at a 140-150 HR then for sure any effort which includes a 30 min time period avg HR 180 is going to feel hard! Assuming an AeT of 165 and AnT of 188 (12% diff) those numbers are high for sure but believable.
The main question here is are your AeT and AnT numbers accurate? I would consider redoing the tests for both at some point. First retest the AeT. When fairly rested try again on the TM and purposefully start with a post warmup HR of say 158-160. This should be quite aerobic and if that drifts only 3-4% or less then I think youre in the ball park. Then at some other point make a max effort (45-60 min) Z3 test and see what your average HR is.