Google has discovered a bug with Google search console reporting. The bug gets actives specifically to performance reports when filtered to discover data.
According to Google, a user might see a decrease in their discover traffic due to a reporting bug but in reality, there is no dip in the traffic of the users.
The issue was present from 8 December to 13 December. The company says the issue has been fixed. Google assures users that this will not affect user interfacing experience.