Is there any شرعي (legally permissible) issue with brokerage work for Umrah, in which one sells it at a higher price than what the company set, without the buyers' knowledge? And does this work fall under the statement of Shaykh al-Islam: "Earning a livelihood from acts of righteousness is not among the practices of the righteous"? And is it obligatory to abandon it?

If you are not an agent for people in obtaining visas, then there is no objection to selling them to them at a price higher than the agreed-upon company price. This action is permissible if it adheres to the Shariah controls, and it is not among the acts of worship concerning which there was a dispute regarding the permissibility of taking a wage. Rather, it is akin to taking a wage for building mosques and the like. There is no evidence to support attributing this statement to Ibn Taymiyyah regarding this matter.