[caww]

Russia’s already relocated 76,000 of the Kursk residents.

I suppose since Ukraine has had no major victory since retaking Kherson (in November 2022) so Zeleski could be looking for some sort of victory or success by going ito Russia directly.

Also Possibly Russian authorities hoped to rally public opinion against Ukraine by not acting early on as they had intelligence of an incursion into Kursk.

[caww]

Also Russian authorities announced that they were moving people displaced from their homes in the Kursk region to parts of ‘occupied eastern Ukraine’.....

[Kazan]

The goal was likely to try and capture the nuclear power plant in Kursk but that failed.

Holding whatever land they have might be a great negotiating tactic...but there is no chance of them holding it.

So, all adds up to Hail Mary attempt to change the course of the war.