Is Quick Assist stuck spinning for anyone else?

There are reports of the same behavior from several parts of the US and Canada. That doesn't establish the cause, but it makes a problem limited to one device or organization less certain.

Check Microsoft's service health information and compare what happens on another network or device before spending too long repairing individual machines.

Remote Help has also been reported as unavailable. That may be worth checking if it's your usual fallback, though the reports don't establish whether the two problems have the same cause.

There were also reports of Microsoft Store service problems around the same time. Could be related, but that's a lead to investigate, not a confirmed explanation for the spinning screen.

Quick Assist is used in social engineering attacks, so some organizations block it. That's a separate security concern, though. The reports here don't show that it was suspended because of an attack campaign.

If you need remote support while investigating, use another tool your organization already approves and follow your normal identity verification process.