What is the ruling on a Muslim praying at home instead of in the mosque due to a bad relationship with the mosque's imam, knowing his injustice towards others, his love for money, and his appointment of his son as muezzin despite the poor quality of his voice?

Mosques are the houses of Allah and the best places on Earth. Allah has praised those who build them and those who glorify Him within them. The man whose heart is attached to mosques is one of the seven whom Allah will shade. You are advised to be diligent in frequenting mosques and not to abandon prayer in them due to the machinations of Satan. As for the imam's transgressions, they are his alone and do not harm you. You should advise him with gentleness and kindness. Even if he does not take heed, you have fulfilled your obligation. Do not deprive yourself of great good because of him. Some scholars have made it obligatory to attend congregational prayer in the mosque, and it is better to avoid scholarly disagreement.