Site URL changed on its own

Hey guys, quick question regarding a domain name issue I am having right now, maybe some of you went through the same problem.

I have a website called thepetsavvy.com and all its pages used to come up in SERP as https://thepetsavvy.com but for a few days now it’s coming more often as https://www.thepetsavvy.com

My google analytics picked up the change and they are asking me to associate my account with https://www.thepetsavvy.com rather than the old one. My analytics are all over the place at the moment. My site traffic tanked a lot. Semrush is showing a subdomain as a result.

Now I need to specify that it somehow coincides with a domain migration from Bluehost to Siteground which seemingly went OK. I contacted Siteground and they said everything looks OK on their end so there is nothing they can do to help.

Question:
Has anything similar happened to you?
Was its related to domain migration?
Is there any way to fix this so as to have all info under https:// only instead of having it split between https://, https://www (and even sometimes https://) ?

Thanks for your contribution, much appreciated!

Eddie

The page I need help with: [log in to see the link]