Let's say this is a correct statistic, idk if it is but ill take your word for it. For one, the UK is far more densely populated, which surely plays a role in arrests and law enforcement. Secondly, a single arbitrary mark of arrests does not prove that the UK is authoritarian and definitely does not prove that Russia is not authoritarian. Other statistics are far more relevant to that point. Thirdly, in the source you provided, the one about the UK, it says "About half of the investigations were dropped before prosecutions".
Yeah, this is a nothing burger.