Site not Ranking for Mobile

One of my websites is ranking #11 for a keyword on Desktop but on mobile only #27.

I checked site speed, mobile usability and it's pretty good(better than the competition which is ranking #1). The site is responsive and has no issues in Search Console either.

Anybody has any similar experience, why could this happen?
I would like to mention that it's not the US market, if that matters.

Also for Desktop it's stuck #11 for months now, even if I have built a lot of back links in the past months it's been stuck for almost 6 months like that.
Any help would be appreciated.

Is mobile first indexing enabled for that site?

If yes, it could be the case where some content or other important elements are visible on the desktop version but are not on mobile.

Just a quick guess, because had a project like that