I have purchased my impact driver two years ago now the driver bit has loosened due to rapid and continuous usage. This was a huge problem for me. I used it for many projects. It suddenly throws away the impact driver bits. This is a thread for safety also. I tried to find the solution by using many resources. Finally, I could find a real solution. You may be interested in that. I have attached it here. That was very used full to me. I hope that will be useful for you too.
Impact driver chuck is with two springs. When the end “U” shape innerspring is bent down by its other side, the ball bearing comes loose. Hence drive bit is not able to hold on to its power grove. Continuously using can arise this problem. But it can fix easily.
When I was driving or drilling, suddenly, my tool and hand throw away. The tool was not retained on the bit. Most probably, this happens when they loosen the screws or take out the drill bit from the hole. I realized this was a problem, and I found each one step by step to fix this.

When you remove part by part, you can see the part like this. I will explain to you how to remove part by part and how to fix it.
Mostly this happens when the impact driver mechanism is activated due to high torque. You can observe it by noise.
How to Fix Impact Driver Chuck Loose?

Remove the retaining ring from the chuck.
I used small screwdrivers. I had to push towards from the top and then pull out. Do not use any method. That will break the chuck.
Remove the washer, rings, spring and outer part.
Then remove the washer, ring, spring, and out portion of the chuck by using your hand easily.
when you remove the springs, you can see the ball a bearing.
Additionally, you can remove the broken bit in this step when you have that problem.


Remove the end “U” spring safely.
After you remove the outer parts and spring, you can see the “U” spring. Carefully remove it without bending that. Then you can see its shape has changed and bent to the one side.
Before you remove out that you can see the ball bearing has come loose.
This can be done for any impact driver such as Dewalt, Milwaukee, Makita, etc.
Bend the “U” end out from the spring
After you take out the spring, you can bend it by using two needle nose pliers and then try to bend the “U” end out from the spring.


Bend the tail end toward the spring
Then you can bend the tail of the “U” spring towards the spring.


Fix the “U” ring and make sure bearing is tight
After you fix the U ring to the tool head, you can see whether the bearing has tightened. If that was fixed correctly you can see the bearing has fully tightened.
Make sure the bearing ball is fixed to the upper.


Check the retention of the driver bit.
After you have done it, you can see whether it has been retained in the driver bit. You can see it. When the bit is mounted, you can hear a “click” sound. and when it pulls, it will not come out.
If the above fixation is not worked, you have to change the “U” spring.
Conclusion
When you are working with the impact driver, you can have to face many problems. Loose chuck is one of them. when the chuck is loose, it will throw away from the tool.
This can be fixed easily if you follow these steps. If that did not work for you, you have to change the spring.
Try this!