Preventing Google Webview upgrades?

Hi there!
As we recently encountered issues with one of Google WebView latest Versions (e.g 76.0.3809.89 ) with issues such as depicted in following link :
We were wondering how we could potentially prevent Google from upgrading its WebView on our U9...
Login in with a Google account and deactivating some updates is to be excluded as we prepare some boxes for clients and we don't wnat to go through configuring a Google Account on each box.
We derive our own .img from official Firmware so the idea would have been to modify something in build.prop for example...
Would any one of you have a clue? If so please share, a solution would be appreciated!