They are generally not something I would recommend someone utilize in retirement. Don't confuse the preferred shares of a split corporation to actual preferred shares issued by corporations.
The key thing to understand is that while they look like preferred shares, they’re tied to the performance of a split-share corporation that holds a single stock or a basket of stocks.
The structure can create higher yields, but also introduces risks you wouldn’t face with actual preferreds.
For example, if the underlying portfolio drops far enough, the safety net protecting the preferred shares can shrink, and distributions could be at risk. They also tend to be less liquid and more complicated than traditional dividend-paying stocks or company's actual preferred shares.
They can work as a bit of a smaller position to maybe boost the yield of your overall accounts, but generally they're financially engineered to provide you with yield but expose you to some additional risks.