The World Cup Qualifier between Brazil and Argentina was stopped early in the first half as Brazilian Federal Police walked onto thepitch to detain four Argentinain players for breaking COVID protocols. The players are based in Britain because they play in the Premier League.
According to NBC's Roger Bennett, the four players who were detained were Tottenham's Cristian Romero and Gio Lo Celso and Aston Villa's Emiliano Martinez and Emiliano Buendia. The problem appears to be that they did not quarantine for 14 days after coming from the UK. The match has been suspended.
It's actually surprising that we haven't seen anything like this before considering all the different travel restrictions in different countries.