Analysis of information sources in references of the Wikipedia article "Double bowline" in English language version.
Because this knot unties so easily, sometimes even by simply rubbing against your body
double bowline is more complicated than the Figure Eight and partner checks are harder to verify. ... single bowline is not safe while the double bowline is difficult to tie but is easier to undo after taking strain
A knot that can be shaken loose to spill of its own accord, such as the bowline ... is an insecure knot.
there are many versions of the bowline, some of which are unsafe for climbing ... Bowline on a Bight, Retraced Through Harness w/ Yosemite Finish ... is the safest option