Is it permissible to swallow acidic gastroesophageal reflux during prayer and fasting when it is difficult to avoid, and is it considered vomit or regurgitation, and am I sinful for not removing saliva mixed with it that fell on the mosque carpet?

Intentionally swallowing stomach acid after it reaches the mouth invalidates the fast and the prayer according to some scholars, and what was corrupted must be made up. However, if it is impossible to expel it, or if it returns overpoweringly or forgetfully, then neither the fast nor the prayer is invalidated. It is necessary to guard against swallowing stomach acid as much as possible and to maintain the cleanliness of the mosque by removing any harm that falls within it.