That error is due to android 7, not the app. Upgrading is the only way to get rid of it, anything else would turn an insecure device into a massive security hole.
Yes, it’s related with OS model. I searched a bit on StackOverFlow and GitHub, but the articles I came across were too technical. I've already added a link to an issue I found on GitHub about this above.
But at least a warning dialog about this problem can be added to the app. Or the app support for devices under Android 8 can be discontinued directly.