Google reminds us that Smart Shopping campaigns will be phased out, and that all new campaigns created in Merchant Center will be Performance Max.
Any new Merchant Center campaigns will now be Performance Max campaigns.
In July, Google Began Automatically Upgrading Smart Shopping Campaigns To Performance Max

Finishing the transition. Google began automatically upgrading Smart Shopping campaigns to Performance Max in July, as we reported. Between July and September, Google accounts would be upgraded.
Furthermore, Google recently announced that any campaigns in the Merchant Center would be automatically upgraded, and that any new campaigns created would be Performance Max. Any campaign settings and budgets will be carried over as well.
Google’s Automatic Updates Are Expected To Be Completed By The End Of The Month
If you still have google smart shopping campaigns running, should you upgrade or not? If you’re unsure what to do or if you should upgrade your campaigns yourself, here’s what you should know:
Google’s automatic updates should be completed by the end of this month. If you still have Smart Shopping campaigns running in Google, use the one-click upgrade tool to switch them to Performance Max.
If you are running Smart Shopping campaigns through Merchant Center, pause them and create a new Performance Max campaign, or let Google upgrade them automatically and check your account for the “Performance Max (Upgraded)” notification.
When the upgrades are finished, double-check your budget and settings to ensure that everything is where you want it to be.
Read Google’s Faqs And The Announcement About Merchant Center Upgrades Here
Why do we care? The constant reminders from Google about the automatic upgrades can be confusing and redundant, but if you’re still running Smart Shopping campaigns, the only thing that you need to do is upgrade them yourself or let Google handle it. The switch to Performance Max should be completed this month.