Cache size keep growing

We hosted the Gorse on AWS with Elastic Cache, and it just eats the whole of our allocated cache and shoots our AWS bills.
Later we changed it to PostgreSQL DB as cache. After a few weeks, it reached 5TB DB.
Number of products we have 10K, and only 0.1 million users.

We find there are 200 million entries in the table sorted_sets. And these entries keep on growing day by day.
Can we have some solution with respect to this behaviour? There are no timestamp field present in the sorted_sets table which can help if there is some issue somewhere and we can remove entries through some script.