I can confirm this is at best a gluten issue, at worst a grain issue. I stumbled on to the correlation accidentally When I realized I had forgotten to take my medication for it (which I felt concerned was "winning the battle losing the war), but had not had grains for a few days and realized I wasn't having issues.
Over the years since then I have done a lot of homework about WHY gluten might be having this effect, and had learned that the issue of Reflux/Gerd is an insufficiency of very acidic hydrochloric acid in the stomach, because it triggers the closing of the esophageal valve involved with reflux/Gerd. I also learned that the ONLY thing that breaks down gluten is hydrochloric acid, and realized there was a connection. But I also realized something was causing the stomach acid to be too weak and that it is not the food, It's likely connected to an Iodine deficiency.
Iodine concentrates stomach acid.
I've been healing my digestion and supplementing with Lugol'sIodine and am experiencing less and less issues with reflux/Gerd on the days that I do still choose to have gluten containing food. I don't get bloated most of the time and I have been feeling better and better.
I'm so glad you found that connection too! It's a great first step. :)