Query performance degraded after upgrade to 19c

We're working on an upgrade project to upgrade our 11g database to 19c. 
The 11g database has been upgraded to 19c on a test server & our application are running test on some of their applications.

During the test they've found that some queries are running very slowly. Below are comparison between the current 11g explain plan and 19c explain plan for the same query. Is there anyway for me to improve the query running on 19c?

Explain plan for 11g

<div>--------------------------------------------------------------------------------------------------------------------</div><div>| Id&nbsp; | Operation&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;| Name&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;| Rows&nbsp; | Bytes | Cost (%CPU)| Time&nbsp; &nbsp; &nbsp;|</div><div>--------------------------------------------------------------------------------------------------------------------</div><div>|&nbsp; &nbsp;0 | SELECT STATEMENT&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; |&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; |&nbsp; &nbsp; &nbsp;4 |&nbsp; 2088 |&nbsp; &nbsp; 38&nbsp; &nbsp;(3)| 00:00:01 |</div><div>|&nbsp; &nbsp;1 |&nbsp; HASH GROUP BY&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; |&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;