Displayed months changed language after V20 upgrade

[Freddy1]

I upgraded an On Premises 3CX V18 to V20 the months in there were still displaying in English. I created a fresh V20 backup & using PBXexpress & the new backup I created a new lightsail instance. Now I see the months in office hours are in a different language, I think Czechian. I also noticed this in active calls.