Ok, I'll lead with the fact that I know this is a cheap lens and they're notoriously difficult/impossible to focus well.
But ... something is strange here.
I took this lens out to try and get some pics of the Jupiter-Saturn conjunction tonight. Camera is a Canon T7i. Used a tripod and a remote shutter release. Focused on the moon to start with, and used the live view zoom to really get a pretty good focus.
Then, still on live view, I click the shutter release. When the image displays, it's obviously unfocused relative to the live view. It's not terrible, but the live view is definitely better. I tried a range of ISO & shutter speeds. Found the conjunction, and got the same thing - could see moons when zoomed on the live view, but the pictures are nothing but blur.
So why is the focus changing between live view and the shot?