Reports are coming out about Russian activity in Belarus, Russian troops and supplies are assembling there and there has been a joint Russian-Belarusian military group announced.
Ukraine has sent a lot of what they had in reserve to the front as well as sending a lot of their newly formed western armed units there so I am not sure how well defended they are in the north now.
But of course it could just be a way to apply pressure and force Ukraine to withdraw forces without them actually invading from the north again.

Though it seems that early on in the war the Russians attempted to blitz Ukraine in a rapid coup which failed then pulled back as they were spread to thin, with the incoming mobilised forces(plus Chechens and other new forces) and the Ukrainians committed more heavily to the east they may feel that they are not longer spread to thin.