MongoDB 5.0.17 Community. We see nearly the same behavior of storage allocation and use for a number of collections with TTL indexes. The storageSize field value returned by the $collStats aggregation stage constantly grows despite the size and count values stay nearly the same.

For example, after subsequent resynchronization of one of our collections we have: count ~ 100M, size ~ 170 GB, storageSize ~ 90 GB.

Having nearly the same count & size every time we see, that storageSize grows slowly but continuously, and finally we get storageSize ~ 400GB, when we have to run another recync cycle to decrease storageSize for this and a number of other collections.

We have never seen such a behavior on our 4.4 version.

What could be a reason of such a strange storage management in 5.0? Do we have any v5.0 configuration options to revert storage management behavior back as in v4.4?