Yep, I've always had a really easy time making ambigrams because of my (natural) mirror writing ability. As in, one day I tried mirror writing and I could just... do it without hesitation.
I have asked a few left handed and right handed friends of mine to make ambigrams, or do mirror writing, and it's quite interesting how easy it is for left handed people compared to right handed people.
Oh sorry, I thought you were conflating the two because the talent you described was for mirror writing.
I'm also left-handed and learned belatedly that I can do mirror-writing with my non-dominant right hand. I'm not that coordinated with that hand, so the writing is a bit messy, but it doesn't seem to require noticeable extra cognitive effort to do the mirroring.
I could also pretty easily read upside down or backwards from around the time I learned to read.
However, I've never found it easy to make ambigrams!