I haven't seen official statement, but I did see a couple reddit threads where Robinhood exercised ITM calls without enough funding in the account, then collected the shares and paid the cash difference.

https://www.reddit.com/r/wallstreetbets/comments/fcqkmo/so_r...

There's also some threads where it looks like it did not go so well...

https://www.reddit.com/r/wallstreetbets/comments/fd2eko/upda...