Has there been any significant use of decentralized mesh communication networks in Ukraine in the last years?

To limited extend by Ukrainian army, more like a fallback method if something happens to Startlink. Mesh networks are getting used more and more by Russian army for coordinating drone attacks and surveillance - they use Chinese modems e.g. 70M-6Ghz/Uper C-X-Ku).

AFAIK a lot of military gear works over mesh networks.