Right, now I remember this Pedestrian area - #54 by david3
So this was implemented Jan 4, which means all updates from that date and on may give a street decrease. I’ve only had a smaller city updated since then, and lost two pedestrian areas. I guess when Stockholm is updated I will also see a decrease.
A tip: set up Notification for cities you are interested in, then you will see exactly what is deleted (and added of course)