The vast majority of customers from applicable batches have not experienced their brake not disengaging (unlocking) when activated.
However, please double check the batch number printed on a white sticker located on the axle between the rear wheels on your pram.
If it is between 18.01-10-17 and 18.07-03-18, please arrange for the brake upgrade to be installed. Search for your local service centre here. If the batch code on your product does not match those specified, you do not need to do anything.