Kalata
Out of the Silent Planet
I don' think that's the reason. If Bruce wanted to save his voice or to sing only ''easy'' songs for him, then Aces High, Flight Of Icarus, HBTN, RTTH would be removed from the setlist. He is still an amazing vocalist!As for Aces High, last im sure its to save Bruce's voice. He doesn't want to be blowing at the beginning of the concert.
And to add more: Aces High was the opener in 2018/2019 and the encore was also not that easy for Bruce - TETMD, HBTN and RTTH. I admire Bruce for putting this song as the last one in the set (because it's one of the hardest songs to sing from Maiden's discography), even though he's obviously tired and does not want to damage his voice with the high chorus at the end of the concert. The performances are not bad, but they need to change it to be the encore opener (to make it a little easier)... although the song along with the Spitfire works surprisingly well as a show closer.