how to revert to previous version of safari

Safari is installed as part of the Mac's operating system. Safari is sometimes updated when a newer OS is installed. Since it normally cannot be individually installed, what you want is not possible, unless you install an older operating system.

Since Safari 15 was auto-downloaded to my Macs a few days ago, the following things are happening:

• Apple Mail will not update—I need to go to the Gmail site on the web to read new emails
• Links from emails or other documents will not open—I click on a link and a new tab opens with my start page; I need to copy and paste the link into the address bar
• My credit cards are being refused until I reopen the site in Chrome or Firefox and reenter the information
• Links from web pages always open in new windows, not new tabs, so I end up with multiple windows and must constantly toggle between them or copy and past URLs

Being forced to resort to another browser has been positive in one sense: I've learned that Firefox, despite its other limitations, is lightning fast, while Safari is slower than ever. But after years of using Safari, there's too much time and effort involved to switch right now.

How can I undo the disastrous Safari 15? I know I'm not alone in experiencing a ton of glitches. Will Apple fix Safari before releasing the Monterey OS? Thanks for any ideas.