British citizens will lose visa-free entry to Ukraine the moment when the United Kingdom leaves the EU
This would only impact a minute number of people.
Might even save some being scammed.
I remember a bloke from Work, he went motorcycling from Bejing back to Netherlands. Considering the time-frame of his trip (3+ Months), he couldn't apply for a Russian visa from the Dutch side, so he had to get one from the RU/CN border at the spot.
First he was delayed because he was not allowed to cross the desert alone. He had to wait for a companion travelling the same road.
He encountered a brittish man with the same intent as he did. Drive through Russia back to Europe.
So when they got to the RU border on the other side of the desert, he got a visa within 2 hours waiting. The other guy (the brit) got denied.
Officially no reason, unoficially because they didn't think brits should benefit from the anti-russian behaviour brittish were showing at the time. (This was a decade ago).
Now the brit had to wait for a guy travelling in the other direction because of .... the desert.
So he couldn't enter russia and couldn't go back either. He was stuck.