Camera replaced several times

When you mean by original having cracked lens, do you mean just the camera still focuses and doesn't have internal dots / not focusing problem?

If this is the case then you simply only need to replace the back camera glass cover. You can buy these online at places like eBay, costs a few bucks and easy to install. (Does not require opening up the phone but at minimum probably just taking off the battery cover.)

Just make sure to clean the broken glass carefully without scratching the lens or getting it in the camera.

I generally use tweezers or a spudger to scrape away the adhesive bonding to the area that holds the rear camera glass cover.

Then inspect the rear camera for any small glass fragments on or near it. If there is any glass fragments around the camera which it moves to focus try cleaning it out as it may cause focusing issues in the future.

Try booting into recovery mode and wiping the cache partition. I find this clears up issues that can't be explained.