I found the older thread on this:
https://www.pprune.org/archive/index.php/t-625919.html
Villas, I can see your contribution but don't agree with your reason that Airbus does this to smooth things out. We can and DO do that ourselves by adjusting the speed. I reckon this is a glitch that has something to do with me being in HDG mode. Just spoke to another colleague flying the same aircraft today, he didn't experience anything of the sort.
On the Boeing, we have FLCH mode. Same concept. Works as anticipated. Full climb thrust, Idle to descend. No chasing the speed.