I got flashing security warning with an ‘Apple’ logo asking me to call

Any and all such notices that appear on a web page, a popup from one, as an email or text message are ALL scams. Do not ever contact them.

Now that you have called and they have your phone number, expect to get lots of related scam calls. When you realize what the call is about, hang up immediately. Do not talk to them for even a few seconds.

Than is very un-Apple-like.

Scams (e-mail, text messages, and phone calls) are getting very good at closely imitating true Apple communications. Always be cautious. These support articles have some guidelines:

About identifying legitimate emails from the App Store and iTunes Store --> Identify legitimate emails from the App Store or iTunes Store - Apple Support

Recognize and avoid phishing messages, phony support calls, and other scams - Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

Avoid scams when you use Apple Cash --> Avoid scams when you use Apple Cash - Apple Support

Apple 'How to identify, avoid, and report phishing' video--> https://youtu.be/SR3Z3fXXjfw

If you are uncertain about a message and a resource provided in that message, do not click on any links in the message. Try to independently verify the resource by going to a support page on apple.com and use that to contact Apple or to verify with the service the message is telling you to use.