An issue existed in the handling of tabs displaying picture in picture video. The issue was corrected with improved state handling. This issue is fixed in iOS 13.4 and iPadOS 13.4. A user's private browsing activity may be unexpectedly saved in Screen Time.
Apple Security Advisory 2020-03-24-1 - iOS 13.4 and iPadOS 13.4 are now available and address buffer overflow, code execution, and cross site scripting vulnerabilities.