Probably, you are not the only one who found that the Outlook Search Bar was missing. Some users who installed the recent Windows feature update following its release are also complaining the same ...

The Toolbar can be missing because you probably hid it by mistake. We will look at how to show the Toolbar in the Outlook web app and Outlook desktop app.

Microsoft will roll out a fix for a known issue causing Outlook for Microsoft 365 to crash on systems where users attempted using the Search bar or Search Suggestions features.