People can have various rates of stomach emptying.

It can be because of taking drugs that slow the stomach like opiates or anticholinergics (Benadryl type drugs also).

Or it can be gastroparesis due to aging or nerve damage.

It can be because of the stomach contents itself, as chocolate and fat delay emptying. Coffee causes heartburn for some.

I can get heartburn from chocolate sometimes.

It can be due to excessive gas being refluxed. Excessive gas can come from bacterial dysbiosis or carbonated beverages,
certain food like the cabbage family, or from nervous swallowing of air, or excessive swallowing of air with food..like soups. I personally believe gas is a huge culprit in many heartburn cases.

I use ginger extract sometimes, but it can REALLY cause a burning reflux when taken at the wrong time or without enough water. You really haven't lived until you have a serious ginger event!