Hi C*,
get a "Pitch-pitch" warning etc.
It may be due to the speed decay during the flare is too much and you end up with a higher NU attitude. The attitude + rate of change of pitch is then very close to the trigger threshold for "Pitch-pitch" warning.
It may be that during manual thrust approaches, you are effectively taking the power off earlier than you are with autothrust engaged. (due to TLs at approach power position Versus being at climb gate with autothrust).
I have in excess of 6000 hrs in other types without ATHR
then close the TLs when you would do so on the other types.