Technically yes, but a lot of it is probably unrelated.

For example in Germany, Merkel is stepping down as party leader after 4 terms but she's not stepping down as Chancellor. In the Netherlands, Rutte is resigning over a scandal involving people getting incorrectly taxed for child benefits, but elections were already planned for March anyway.

Maybe there's more to some of the others, but a bunch of these are just suggestive timing.