A case so shrouded in propaganda from both sides that you should question anything you read about it.

In the Navalny case, propaganda is state sponsored and present on both sides. Russian propaganda is scrambling to cast at least some amount of doubt on the poisoning of Navalny by Russian state actors. Propaganda in the West is, in the meantime, engaged in a kind of white-washing that tries to show Navalny as a hero and a real opponent to Putin, which is false.

https://www.outputblog.de/world/2021/03/15/Alexei-Navalny.html