Can anyone tell why there are v1050 maps released and quite quickly again v1051 of the same region? This is just for example, haven't checked if this is true in v105* maps, but were real at least in v104* maps for Europe region.

Is it some kind of "quick patch", as in computer world? If so, seems quite a lot of these fixes.

... the difference may be in the change of speeds of the countries ...

Speeds are so often wrong, that I doubt that a new map is published just because of that.