Male bladder incontinence at night. How do you prevent leakage at the waist when using adult tab-style brief?

This goes back almost 30 years, but when my boys were in diapers, I just folded down the top edge of the diaper to face inside. The leaks magically disappeared.

I don't have any experience with men in diapers over the age of two, but it's worth a try, combined with an extra pad.

These Washable Leak Resistant Adult Pull-On-Cover Pants are meant to wear over the disposable incontinence briefs to help prevent leakage. They work for our LO. https://tinyurl.com/27mrcnxh

They make incontinence pouches that fir over the penis for light bladder leakage, I wonder if using something like that in addition to the brief would help to keep things contained? Like these:

https://www.amazon.com/Top-Incontinence-Pouch-Level-Pack/dp/B015WR7X0U

There are also condom catheters - those are pretty much just what you might imagine them to be.

They do make pads for men that you can place inside his diaper to help absorb more pee, and the actual Depend type diaper would probably hold more in as it fits closer to the body.
You may also have to get up a few times over night to change him so he won't be so wet in the morning. Also make sure that you have several waterproof pads under him, so if one is wet all you have to do is pull it out from under him and he will be on the clean one.
My husband was severely incontinent for the last 4 years of his life, and after trying all the bladder spasm medications and having Botox put in his bladder with no success, his urologist recommended that he have a supra pubic(permanent)catheter put in which was a Godsend for sure. I then only had to empty his catheter bag once in the morning and once in the evening, which made life easier for us both.
Good luck in getting this issue figured out.