What is the ruling on publishing a list of halal products that later undergo a change and become impermissible, and to what extent is a verbal inquiry to restaurants about the permissibility of their food sufficient?

If the people of a country are Jewish or Christian, the general rule is that their slaughtered animals are permissible to eat, based on the Almighty's saying: "The food of those who were given the Scripture is lawful for you." However, if it is known that they slaughter animals by impermissible methods, such as stunning or shooting, then it is not permissible to eat them, even if a Muslim performs the act. If there is doubt about the method of slaughter, it is not permissible to eat it, as the default rule for slaughtered animals is prohibition. It is permissible to eat them if the person of the Scripture states that he slaughtered it according to Islamic rites.

As for non-meat products, the general rule is that they are permissible and do not require ritual slaughter. Nothing from them is forbidden merely due to doubt, unless it is highly probable that impurities are used in them, such as pork products and carrion. In such cases, one must investigate and read the product ingredients to avoid anything containing impurities. The same ruling applies to products marketed online; it is not permissible to market what is unlawful.