Getting “400 Bad Request” error intermittently on our site and this is happening due to the size of the Adobe cookie ‘s_pers’. This cookie is being set by "Cookie Combining Utility v.5" plugin in Adobe s_code file. Please suggest any resolution.
As far as I am concerned, Analytics itself doesn't make large cookies. If you are getting cookies that are large in size then I am assuming it would be like a custom plugin you might have implemented storing some values in a cookie that keeps appending things. Other scenarios I could think of is: retrieving values from the URL; concatenating values to pass to Analytics et cetera.
I believe you would need to evaluate your plugins you are using.
Also, we would be needing steps to reproduce, and other information to further troubleshoot the issue. Hence, would suggest you raise an incident with client care team[email@example.com] to further help you on this.