Interactive Brokers: Changes in currency conversion for Cash accounts in April 2024

I bought 100 stocks VT by selling deep-in-the-money option and converting Euros to USD. As usual, the option was exercised the following night, but then IBKR did weird things converting remaining Euros in the account into Dollars. I suspect their auto-conversion kicked-in: for cache accounts they do currency conversion themselves if there is no enough settled amount of USD

But what puzzles me, as settlement for stocks like VT is now 1 day and for FX operations it is 2 days, it means that for 1 day I’ll be short of dollars anyway. How is it possible in a cache account? I am afraid they would do rare things like liquidating my VT holdings to cover for that. Anyone has experience with that? Like if you buy VT having only Euros or Franks in your account, does it work OK?