Hi @Shrinidhi_Rao and welcome to the MongoDB community!!
The chunk balancing between the shard servers depends on the number of chunks in each of the shard servers and is not dependent on the hardware of the machine. or the document or collection size of the chunks being migrated.
The MongoDB cluster balancer deals with redistribution of the shards evenly among the other shards of the sharded collection.
The balancer migrates the chunks from shards with higher number of chunks to shards with lower number of chunks till there is an even distribution of chunks between shard servers.
Please refer to the documentation of Sharded Cluster Balancer for further understanding.
Let us know if you have any further questions.