The debate whether or not weak abs can cause back pain has been going on for a while.
To keep it simple if your core was “weak” you would have a hard time standing up. You would essentially just fall over limp.
So I think “weak” is a bad word to use when you’re talking about lower back pain.
The terminology that I use with my clients is. alack of coordination and endurance for their individual lifestyle. The key to building a resilient support structure is for it to be able to withstand the demands you put on it. Having more endurance and awareness of how your core is used when moving, exercising and doing what are now “risky” activities that cause low back pain is critical.
So can having weak abs cause low back pain? Yes and no but reframing the way you look at the core is the most important part of this answer.
One element to this is how you’re tuning your core brace to fit the demand.
I did a write up on this you can check out here!