Krugman has this to say about it:
For those not familiar with how financial markets work, US Treasuries are the ultimate safe asset, used as collateral for everything. Even a hint that some Treasuries might not be honored could bring everything to a screeching halt
Musk and Trump are both in the habit of stiffing people they owe money. If markets even suspect that this habit will extend to Treasuries, God help us
As far as I understand, the recession that occured in 2008 era in Europe at least was in part due to lowered exports to the USA. But this time the EU economy is more diversified in part because of that event, and preparations had already been made because of Trump’s first term.
Again, not an economist, but my understanding is still this wouldn’t impact us that much compared to others.
And even the last recession that happened in the USA wasn’t the worst that affected Europe. That was '92.