Some internal old links converted to non-www, others to www

Hi I shifted to https:// a couple of weeks ago. I used your plugin and liked its simplicity a a lot.

However, recently while going through my numerous past blog posts, I noticed that some internal links inside them were converted to https://www.mysite.com/subjectmatter, but others were converted to https://mysite.com/subjectmatter

Any reason why your plugin takes two approaches to past internal links (i.e., missing “www” in some)?

Thanks.