Technically, the leverage at none of these brokers is unlimited.
For example, at Exness, when I traded with them in the past, they would reduce the leverage during active trading hours, on almost every news event, for 1 hour or more.
So, almost every day during the Frankfurt & London open, the leverage was 1:200, not unlimited.
You will see a message like the one attached in your mailbox, about change in Margin Requirements, the affected instruments & the hours.
It is not just during news, many times during active opening hours, you will see leverage restrictions. So, no, the leverage is not unlimited.
I assume that other unlimited leverage CFD brokers do the same as well, in order to manage their market risk.
But in any case, I don't think you should be using unlimited leverage.