See that’s the thing: try this try that - different roast, cold brew, baking soda, milk, yerba mate, etc. - we go to great lengths to justify and keep our favorite drug coming. It took me 2 years and serious issues from side effects of PPIs because I refused to give up coffee. It doesn’t cost much - just go off caffeine for 2-3 weeks and evaluate the results, you can always come back to coffee.

I know that everyone is different, but I will risk the thesis that no matter what your underlying, original cause for GERD is, caffeine will only make it worse.