It's... really not that hard.
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Uninstall the new app, download the old app from https://www.apkmirror.com/ (which is basically an archive of most apps downloadable from Google Play).
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Use an app like APK signer to change the app's "signature" so it doesn't automatically update.
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Install it.
It takes like 10 minutes at most.
I did exactly this with the Discord app last year when they suddenly changed the app's entire layout.
What I'm talking about was when they changed the Android app to behave more like the iOS app. It was a buggy mess when it first launched. It's much better now, though. I've since updated my app to the current version.