it is definitely a risk primarily for EZY, since as has been said they will need a new EU based company that is 51% owned within the EU. I don't have access to the domicile breakdown of their existing shareholders, but if when the UK ones are added to the other non-EU shareholders it comes to more than 50% they have an issue.
TUI AG likewise have a similar issue, since 15% is a Russian shareholder (so non-EU) 6% are private investors (mostly the Directors & employees of former TUI Travel PLC so UK) then 76% are institutional shareholders (primarily coming from the TUI Travel PLC days so heavily UK biased)