The bicarb works together with the vinegar.
The problem with heartburn isn't too much acid, in fact, it's not enough.
If you can explain how adding a neutralising agent to an acid will reduce the pH (when the intention is to increase pH to relieve the pain caused by higher acidity) I'm all ears!
When you take prescription or over-the-counter antacids, you're disturbing the natural flora in the gut.
In h.pylori-related gastritis, it is true that antacids (e.g. H2 blockers) may not be fully effective without the appropriate antibiotics. But this is more likely in long-term
use. One tablet is unlikely to have much effect.
What causes indigestion is excess alcohol, refined sugar, processed food, white flour, etc.- all the crap we all love and crave.
and which - wait for it - raises gastric acidity in many cases!