If the issues you mentioned are indeed caused by iOS, it's likely that numerous users who have upgraded to iOS 16.4.1 (a) are experiencing similar problems. However, in order for the community on this forum to provide helpful responses, it would be beneficial for you to specify the nature of the issue you are encountering. Without this information, it may be difficult for others to address your concern effectively.
With the limited information that you have provided, It is hard to even guess the problems faced by you.
You may get faster and better responses to your query by --> Writing an effective Apple Support Commun… - Apple ...
Please re-post with detail so that someone else can help.