Russian players were barred from Wimbledon upon the recommendation of the British government however it seems the ban is not only for Wimbledon. That is according to Rublev who revealed that Medvedev was asked to participate in the Laver Cup but the government 'hinted' that it probably would not work:
"Not me, I know that Daniil (Medvedev) - yes. But there is also the British government, and they hinted that it probably won't work."
Both Rublev and Medvedev played at the Laver Cup in Boston last year but neither returned this year, quite possibly due to the Government interfering.