I say “recently” in a relative way, more so countries that have split in the last century. Places like North and South Korea, Taiwan and China, former USSR states, etc.
Has enough time passed that these countries separated have major changes in their languages yet?
They’re not THAT different. In fact, they both used to use the same system, but mainland China simplified a bunch of characters to combat illiteracy and make writing easier while Taiwan did not. The pronunciation did not change however and they can still understand each other.