@ascentale @semitones @bikenite
Building core strength can help with this - when your core muscles aren’t doing their job holding you upright and resisting forces in all kinds of directions, your back has to do it instead, and it’s not as good at it! Crunches are not recommended these days but things like planks, bird dogs, “dead bug” exercises, etc. “functional core strength” as an exercise search keyword.

And if that fails, or if you can afford it probable regardless, see a physical therapist (not a personal trainer) who can assess whether that’s your actual problem or something else is, and tell you what your specific body needs and make sure you’re doing the recommended exercises right.