Vilas, many thanks for the reference! I always wondered what ‘crazy’ logic the Airbus was following. I have seen this behavior on both 319’s and 320’s, CFM CEO’s and LEAP NEO’s. It typically happens when you have been flying on a higher selected speed when leveled off and pushed for managed speed as soon as you get further climb. The engines will almost go to idle initially.
The opposite is also true, if you want a faster thrust response after selecting CLB, select a higher speed.