It makes no sense why Putins government would poison Russian people here in the UK.
It makes pretty good sense given an individual who has instructed his subordinates that anyone who betrays (ie leaves) the Russian secret service should die for it.
The man who was the victim of the most recent assassination attempt in England had left the Russian secret service. (The woman who died was collateral damage.)
Others of Russian extraction or with Russian connections who have been killed/inexplicably just upped and died here have also been opponents of Putin. I would certainly say Alexander Litvinenko was killed by ingesting polonium, for example. There has been more than one lawyer who was representing someone of whom Putin disapproved, or journalist who was asking awkward questions, or close friend of a Russian businessman who had already died abruptly, who died suddenly of mysterious causes or in rather coincidental "accidents", or in one case "committed suicide" by stabbing himself repeatedly including in a couple of places he would have had seriously difficulty reaching.
Naturally enough, Putin says this was all masterminded by the UK in order to make Russia look bad. Which bit of the UK he doesn't specify, nor why anyone would bother to make Russia look bad when he's doing such a good job already.