We had the same issue after we upgraded to Aurora 2.11.1. The issue is mainly due to a bug fix implemented on 2.11.0. You have to contact the AWS support and raise this concern and they will apply the fix internally by disabling a particular parameter from hardware level.
Please refer below for more information :
A new dynamic configuration option, innodb_deadlock_detect, may be used to disable deadlock detection. On high concurrency systems, deadlock detection can cause a slowdown when numerous threads wait for the same lock. At times, it may be more efficient to disable deadlock detection and rely on the innodb_lock_wait_timeout setting for transaction rollback when a deadlock occurs. (Bug #23477773) More information on Innodb deadlock detection can be found in the MySQL documentation.