I shoot video 4k 30fps to check if my action3 has focus issue. However, I have no idea if it has problem. Does it have focus issue?https://1drv.ms/v/s!AqRnfCqWX0tP8l2R43QynO9Ik-wj?e=03Joaq

The A3 isn’t so sharp at close focus so people say on this forum to avoid close shots because it’s an action cam and not designed for close shooting. In spite of having a front screen, I find selfie type shots a little too soft for my liking, so it’s probably best not to do anything close with it.

It is a bit hard to judge in this low light situation, but to my eyes it looks ok.

In answer to your specific question . No you don’t have a focus issue. It is a fact that the only units I have seen since the last update with a focus problem are two on this forum and both of them were DIY botched attempts to move the focus.
Owning all 3 action cameras I can tell you the A3 focuses just as good or better than previous two.

the photo grab is good,  the best thing we can do is head outdoors at high noon on a sunny day and take a shot no matter what it is.  and the shot looks good, then no worries.I feel you got a good camera, but  we'll leave that up to you to decide.

FISH

Hi, CounselingPeter. Thank you for reaching out, and we apologize for any inconvenience caused. We recommend that you update your firmware to the latest version. And to further check this, we need to ask for a sample that will help us determine whether the camera has soft focus issues. Here are the recommended parameters:
1. It is recommended to shoot in a well-lit environment and capture the back of the product’s package box (including Standard Combo and Adventure Combo).
2. Set the parameter as follows:
a) ISO: 100-200;
b) EV: 0; Make sure that the ambient brightness is bright enough;
c) FOV: Wide
d) Resolution/Frame Rate: 16:9 & Steady Disabled & 4K25 or 4K30;
e) Fixed Capturing: Ensure the camera and outer box remain fixed during capturing.
If possible, kindly offer us the serial number of the Osmo Action 3 via PM for confirmation. We look forward to your update. Thank you, and have a nice day.

Firstly you are shooting in a dark indoor environment. That’s not what this action cam was designed to do.

Take it outside on a sunny day and shoot some action shots, which is what it’s designed to do. If it’s blurry then you’ll know!

If you want crisp close up indoor video, buy a DSLR!

I can only agree with the previous commenters. DJl checked some of my test shots. During this time I documented two bike rides. All in bad light conditions. The results were good enough for me. Other videos shows that with better light the image gets more sharpness. I'm confident, that my OA3 doesn‘t have focus issue - equal to the DJIs feedback. We have to wait for better light conditions and don't only read in this Forum.