Are worshippers sinful if they perform prayers in a garage that is licensed as a mosque, given the existence of a new and large mosque built nearby?

A garage becomes an endowed mosque (waqf) if its owners dedicate it verbally or in writing with the intention of waqf, or if they give general permission for people to pray in it. It is stated in Al-Rawd al-Murabbi' that a waqf is valid through both verbal declaration and actions that customarily indicate it, such as someone who designates their land as a mosque and permits people to pray therein. If the garage has become a mosque, then there is no harm in praying in it. Indeed, it might be preferable, as it is older than the other mosque, for one of the criteria for preferring a mosque is its antiquity. It is advisable not to multiply mosques unnecessarily in a single neighborhood to avoid fragmenting the Muslim community. A second mosque should not be built unless the first mosque is no longer sufficient to accommodate the worshippers.