Can these be used without any problems Mavic Mini ? Or are there any better solutions ?

For me yes, this one
https://www.aliexpress.com/item/4000509980745.html

Very light and elegant in flight, it doesn't get in the way of the antennas. As little as a plastic cover might add I still prefer having nothing obstructing my Mini antennas.

Yes they can, not sure if weight is going to be a problem if your drone is not registered, but I wouldn’t worry about it, go for it they’re a good solution .

Hi. Thank you for creating this post. I hope that our valued DJI co pilots, can provide you the best information for this inquiry. Just a friendly reminder, DJI does not recommend to use any third party accessories on the said drone this may affect the performance during flight. In addition, the said accessory may trigger the Payload mode and will limit the performance of the drone during flight. Thank you and safe flying.

https://forum.dji.com/thread-208425-1-1.html
https://forum.dji.com/forum.php?mod=viewthread&tid=206915

Very happy with mine.

https://forum.dji.com/thread-208425-1-1.html
https://forum.dji.com/forum.php?mod=viewthread&tid=206915

Very happy with mine.

... oops!!!!!

They are convenient for storing the drone in its case?

Renato61 Posted at 3-3 23:58
They are convenient for storing the drone in its case?

Not in the Flymore Case, nope.
You have to remove it or destroy your case (cut holes in it).
I bought them too and found out that I literally never use it.

You have to remove it or destroy your case (cut holes in it).

I cut holes in my front door to install a new deadbolt... I don't think the door was destroyed.  My link above showed my "mod" to the case... original function is maintained and enhanced at least for me.

I am a lifetime DIYer and my house still stands.  

I bought them but use them infrequently since I learned how to hand launch and land.  Luckily they pop off without too much bother.  They do add some weight and I noticed a bit less battery time when using them but otherwise no issues with flying.

Akirasho Posted at 3-4 04:05
I cut holes in my front door to install a new deadbolt... I don't think the door was destroyed.  My link above showed my "mod" to the case... original function is maintained and enhanced at least for me.

I am a lifetime DIYer and my house still stands.

great job

red squirrel Posted at 3-4 06:02
I bought them but use them infrequently since I learned how to hand launch and land.  Luckily they pop off without too much bother.  They do add some weight and I noticed a bit less battery time when using them but otherwise no issues with flying.

This confirms my theory: to contain the weight and duration of the batteries, the MM has been designed to the limit and in case of wind or other problems it ends badly.