Accept Encoding header is not removed when the request is load balanced to the backend with Remove Accept Encoding knob checked under the compression settings of a HTTP profile.
This is just a logging issue and in the actual request that is being sent to the server, the Accept Encoding header is being correctly rewritten. The behavior can be verified through a VS level pcap.
Ref kb: https://docs.vmware.com/en/VMware-Avi-Load-Balancer/30.2/Monitoring-Operability-Guide/GUID-35BE1A76-C9F3-4A6A-9F3D-D2EA0776844F.html
The logging issue will be fixed in a future maintenance release.