pop-up notification warning virus and urging using McAfee (which I don't have)

Today I started getting pop-up notifications on the upper right corner of my MacBook Pro screen when using either Safari or Chrome. The messages tell me my operating software is infected with at least five viruses, my iCloud may be infected, and and I should immediately turn on my antivirus (specifically McAfee) software. I don't have any anti-virus software on my computer (that I know of). My operating system was just updated last night to Mac OS Monterey version 12.7.3