Beware, the play store version shows full screen ads, auto redirects and needs contacts permissions.

Is there any proof for this, apart from those bad reviews? The blog mentions another (now removed app) with the package name com.qrcodescanner.barcodescanner, not the open source one at https://play.google.com/store/apps/details?id=com.google.zxi...

I believe these bad reviews might be a result of the malware app pushing bad reviews to the zxing app page on google play, using an in app 'rate this app?' -> low rating -> send to the zxing app in Google Play (instead of the malware app in google play).

As noted above, I believe this to be the case. I had the other app and started receiving full page ads for it. Totally different developer, but same app name. I am no longer able to find that app in the play store.

Ah, looks like mine installation is actually from FDroid, and never realised.

I've installed from Google Play, and never seen any ads. It has contacts permission, but that's because sharing contacts with a QR code is something I use it for frequently (it can generate codes as well as scan them).