Grantelbart
this is czechoslovak and not old Czech, is it?
I think I see what you mean, yes. Good catch! This slightly different, older font was used on plates up until around the Velvet Revolution of 1989. Czechoslovakia ceased to exist on 1.1.1993, but the district-based license plate system was kept in both Czechia and Slovakia. These plates are still valid in Czechia. Slovakia, on the other hand, discontinued the system in 2005 and mandated all cars to be re-registered with their own new license plates, so chances of meeting a car with Czechoslovak-style plates of Slovakia's districts are effectively zero.
As far as I know, keeping older-system plates valid in various countries is fairly common. You can spot old cars with original plates in Italy, France, Spain, Poland, UK, etc. USSR plates are still valid in Russia, Ukraine, Belarus, which I personally find fascinating.