Have you removed the cloud search service application before?
Statement from Microsoft:
“The search topology of the cloud SSA consists of the same types of search components and databases as the search topology of a standard SSA in SharePoint Server 2016. But there are some differences.”
If you have removed Cloud Hybrid Search, you need to reconfigure the Cloud Search Service on your SharePoint 2016.
For better understanding the Cloud Hybrid Search for SharePoint, please refer to the following articles:
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