I don't think the steering is heavy at all. It has what I'd call a less delicate feel at low speeds versus the various previous Mazdas I've owned or driven, but at regular road speeds it to me is fully responsive and "very Mazda". I actually find the steering feel with turns and on curves more appealing than my 2019 CX-5. Just feels more...solid, maybe, is the word, not that the CX-5 steering was vague or anything. To me, that perfectly fits the more offroad, somewhat rugged appeal of the CX-50.
Generally speaking, I've found some of the CX-50 criticism out there odd...really minor things or things that simply fall under personal preferences vs actual issues with the car. Plus with the Internet and all the individuals now who fancy themselves critic or reviewers, we lose the experience level of true critical thinking and instead have opinion masquerading as facts or people finding something, anything problematic to generate those clicks...best thing to do is to find a dealer willing to give you a test drive so you can determine how well the CX-50 or any vehicle meets your own individual expectations.