office 365 – Passing parameter in Update-FederatedHybridSearchForM365.ps1 script for hybrid search with SharePoint 2016

There is a notification from Microsoft about the Hybrid search update which says if we use hybrid search we must execute the Update-FederatedHybridSearchForM365.ps1 script before October 1st, 2021 otherwise your hybrid will stop working. The script can be downloaded from here.

Script execution parameter format:

Update-FederatedHybridSearchForM365.ps1 -HybridWebApp (YourHybridWebApplication) (-Force)

Description about the -HybridWebApp parameter

The internal URL of your on-premises primary web application, such as http://sharepoint or https://sharepoint.adventureworks.com.
This value is a full URL using the proper protocol (either http: // or https:// ).
This is the internal URL of the web application that you are using for hybrid functionality.
An example is http://sharepoint or https://sharepoint.adventureworks.com.

My question is – in our SharePoint on-premise environment, inside the cloud search content source we have configured five web applications for the hybrid search functionality, then out of these five web applications, how to justify which is the primary web application or should we execute this script for all the five web applications?

Anyone could please share your experience with this if you have already executed or know about it.