The US-based think tank Institute for the Study of War says a Ukrainian counteroffensive has degraded Russia's logistics and administrative capabilities in occupied southern Ukraine.
Russia has been preparing annexation referendums in the southern Kherson and other regions.
But in Kherson, a senior official of a pro-Russian group said the referendum plan has been halted due to security reasons.
The think tank said the decision to pause the plan indicates a high level of disorganization in occupation forces there.
Ukraine appears to be continuing counteroffensives while focusing attacks on the Russian military's supply routes in the southern region.
Britain's defense ministry on Tuesday said that based on Ukrainian media reports, the number of Russian drone attacks in Kherson has sharply decreased.
As for reasons, the ministry said Russian drones have been lost in combat, and international sanctions have resulted in a shortage of drone components in Russia. The ministry said the limited availability of drones is increasingly hampering the country's military operations.