Solr index size has increased in solr 7.7.2

[Rajdeep Sahoo]

Hi all
We are migrating from solr 4.6 to solr 7.7.2.
In solr 4.6 the size was 2.5 gb but here in solr 7.7.2 the solr index size
is showing 6.8 gb with the same no of documents. Is it expected behavior or
any suggestions how to optimize the size.