How similar Russian and Ukrainian military uniforms are? For that matter, they both look a lot like US, UK or French battle dress. In Ukraine, both sides have to tie swatches of colored cloth on their arms to identify whose side they’re on! It kind of defeats the whole purpose of camouflage, doesn’t it? And it looks like everybody’s headgear is remarkably similar to the old Wehrmacht Stahlhelm.

I suppose, the combat environment will act to select for a certain look, not to mention the local vegetation and climate. It used to be that military uniforms were bright and colorful, so you could distinguish friend from foe at great distances, and so you could quickly locate your own unit in the confusion of battle. But once infantry weapons became highly accurate at long ranges, blending into the landscape took precedence over everything else. Olive drab, desert khaki, field gray, seasonal color cammies, etc.

Israeli troops have started wearing baggy hats (like chefs wear, but in dark colors) over their helmets to break up the distinctive outline of the round helmet in urban landscapes.

https://www.timesofisrael.com/ukraine-to-get-israeli-clown-hat-helmet-covers-report/

In an aside, I have only seen these helmet covers on one other military outfit: In the SyFI Dune miniseries, the Sardaukar were issued this headgear.