Typical China tooling----Chinese metric threads are too loose fit. Take almost any bolt and screw a nut on. Excessive play can be noted! With a quality bolt and nut, There will be only slight movement and the bolt will break not strip when over tightened.
With that being said, I would replace with a higher quality stud and nut--NOT CHINA--and use caution when tightening.
I have worked on chainsaws where I had to use a 3/8 pull handle to loosen! Way too tight and unnecessary.
I think some people have a chain get loose and think the bar nuts were not tight enough, when in most cases, bar nose was not lifted or they adjusted the chain too tight and backed off the adjustment screw.
Backing off is ok as long as it is backed off to far and then tightened and stopped when correct adjustment is met.
Adjustment screw helps prevent bar movement.