> Why did they suddenly develop an appetite for territory in 2014?

Did they? They took a chunk of Georgia in 2008 (https://en.wikipedia.org/wiki/Russo-Georgian_War) and have been actively occupying some of Moldova since 1990 (https://en.wikipedia.org/wiki/Transnistria_conflict).

They have wanted it since the fall of the Soviet Union and access to the Black Sea has immense strategic value to them. They only had geopolitical (and local political) cover to get it in 2014 and 2022.