Some positive effects, eg making it easier to vote by proxy.
Some negative effects, eg through the misuse of hacked information.
The interference of foreign powers in the election processes of democratic countries is worrying.
There is a need for a European Code of Conduct to govern the use of digitally-sourced information for political (including electoral) purposes. This could be an annex to the European Convention on Human Rights and/the Fundamental Charter on Human Rights. Or, preferably, it could be completely separate and policed by a separate supranational body. This may be viewed as an extension of GDPR.