I had the same situation as you and the same thoughts. However, I dared to continue posting the changes.
When I turn to crashes and ANR, I see that it still calls my existing versions (your 2.14.2 and 3.0.21) as "Current production" +, I have my new version (your 3.0.22) as Phased Deployment. Therefore, from this, everything seems good.

I also just confirmed that people see the existing latest version (your 3.0.21) on the Play Store (and some people see that the version is deployed (your 3.0.22)).
Therefore, I find it safe to do multi-threaded deployment of an APK like this. :)
Roy solberg
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