Got an email from icloud@insideapple.apple.com stating that my icloud was upgraded to Icloud for free. Is this legitimate email

Yes, it’s real.

(No, you didn’t got a message indicating your iCloud was upgraded to iCloud. You got upgraded to iCloud+. Folks that pay for iCloud got that same upgrade to iCloud+. You’ll be paying the same for iCloud+ as you paid for iCloud.)

Phrased slightly less confusingly, the free tier is now known as iCloud, while the paid tier is known as iCloud+.

Some new features have been added.

Info on those iCloud+ features are available near the end of this webpage: iCloud - Apple

Ragbagg wrote:

if the upgrade to Icloud plus is free, why when I click on it, does it say it will cost $9.99 per month?

You already have iCloud+, if you were paying for iCloud storage. iCloud+ is the new name of the paid storage tier, with a few new features. If you decide to upgrade your iCloud+ storage (to more iCloud storage than you’re already paying for) then that upgrade will cost more.

if the upgrade to Icloud plus is free, why when I click on it, does it say it will cost $9.99 per month?