It's possible that your coffee machine was not properly rinsed after descaling.
To rinse the pipes of your coffee machine use the hot water function described in the guide below for 2 full tanks of fresh clean water.
Turn the appliance on by pressing the ON/OFF button.
Wait for the OK indicator light to come on.
When the OK indicator light comes on, turn the selector dial to the position and, at the same time, rotate the steam dial anticlockwise.
Hot water is delivered from the cappuccino maker.
Note: You should not deliver hot water for more than 60 seconds.
To interrupt delivery of hot water, rotate the steam dial clockwise and turn the selector dial towards the standby position.
Remember that hot water delivery should not be done for longer than 60 seconds.