Mongodb v4.4.29

I have a replicaset with Single Primary, 2x Secondaries. All three are hosted on AWS using t3.large instances, with volumes attached formatted as XFS.

But i noticed 2 weeks ago the disk space usage kept increasing for the secondaries.

Upon further investigation if found that size of one of the database is the only difference, the data inside that database is hpdated every minute.

Other than that there is no replication issue, tried launching another machine and synching it from primary resulted in same bloated disk usage.

Is this normal behaviour? If not what can cause this to happen?