What is relation between user throughput and APN-AMBR?

Hi Experts,
What is relation between user throughput and APN-AMBR?

Throughput is limited by AMBR.

Yes. @RFSpecialist, is it set on Core side?

Yes. At PGW.

In HSS per IMSI based.

PGW enforces it. UE-AMBR and APN-AMBR in HSS profiles per IMSI.