It can't be related to iOS 16.4.1 (a) update.
If the issues you have described are a direct result of the iOS 16.4.1(a) update, it is highly likely that a substantial number of users who have performed the software upgrade are encountering a similar problem.
Based on my understanding and experience, it is highly unlikely that iOS updates would introduce issues that affect the day-to-day functioning of the device. iOS updates are typically designed to enhance performance, address security concerns, and introduce new features, rather than causing operational difficulties.
Without a precise understanding of the underlying issue, it may be challenging for forum members to provide targeted solutions to the difficulties you are encountering.