Highlighted words in Find/Replace are showing on screen in all apps

Microsoft Office 2019 for Mac has reached the end of mainstream support and no longer receives updates or compatibility patches for newer macOS releases, including Tahoe 26.2. As a result, visual anomalies such as the “floating highlight artifacts” you are experiencing are most likely attributable to incompatibilities between Office 2019 and the updated graphics frameworks introduced in recent macOS versions.

https://support.microsoft.com/en-us/office/microsoft-365-office-2021-and-office-2019-support-for-apple-silicon-c55b603e-14a6-4b69-bdc0-2bb4c9a36834