Z Zulu time on L sign incorrect?

Hi,
I read the time on the L sign on the map next to my house and the time is followed by “Z” meaning Zulu time. I see two measurements after each other but is is exactly one hour earlier than from what I think when it happened, that there was an IMSI catcher. Are you sure the time is applied correctly - also summer aswell as winter time - to this map?
Sincerely,
Unique