Google Analytics 4 for Blogger keeping Universal Analytics

I have tried to update my Blogger blog to the new Google Analytics tracking (GA4). But I have noticed that my old tracking with Universal Analytics was discontinued (data won't be fed).

Here is the solution I have come to fix it and keeping using UA and GA4 tracking in parallel.

How to rename All Web Site Data in Google Analytics

I have been playing around with Google Datastudio for reporting my blog and AHK Homepage metrics.

I want to use the same report for both data sources and simply switch the data source in the report.

Unfortunately both data sources are shown as "All Web Site Data" and it is hard to identify.

How to copy/ duplicate a google analytics dashboard

I have been looking for this one: How to copy/ duplicate a google analytics dashboard

Blogger: Set up Google Analytics to new dynamic tag (gtag.js)

I got this email by Google Analytics:

I thought my Blogger blog was properly set, but checking at the page source code it wasn't.

Blogger: Analytics issue because of mobile views

I've noticed following trouble with Blogger and Google Analytics:

A same page will have different analytics wether it is opened from mobile or not.

I present here a solution to fix this.