If you implemented GDPR, especially via a WordPress plugin that utilizes an explicit opt-in cookie notification, you likely have seen drops in your traffic in GA.
MonsterInsights has announced that tools or plugins that make compliance to GDPR cookie law and policies easier could result in a drop in traffic, page views and more.
This means pageviews could be lower, sessions shorter and bounce rate could appear lower than it actually is. Additionally, you will be missing source data and your goals could be affected.
A site with an explicit opt-out would allow users to be tracked until they took action. However, it is possible that an explicit opt-out versus an explicit opt-in is not sufficient for GDPR compliance.
Learn more from Monster Insights.