Gallbladder malfunctions can be the result of obesity, poor dieting, losing weight too fast (so yes if you had a lot of weight before, you’re not exempt!), OBC (speaking from experience!), food allergies (which is really just a symptom of gut imbalances), parasites, …
These are just a few causative factors toward a dysfunctional gallbladder.
To add to this, I might say that if you had a lot of weight before, your gallbladder could use some support! Also, food allergies are just a symptom of underlying causes such as gut imbalances.
If you HAVE any of the mentioned factors, have you ever done anything to help support your gallbladder?