What is the ruling on previous fatwas that were adopted based on ease, and are they considered void, and must one make up the days on which one broke their fast by swallowing phlegm based on a previous opinion that is considered weak?

The preponderance in matters is relative, and it is obligatory for the layperson to follow a scholar whom he trusts. If the scholars are equal in his view, he may adopt the easier opinion. And whoever performs an act based on a permissible imitation, there is no sin upon him, nor is he required to make it up.