Is a Muslim sinful if he returns to his home country, where injustice and moral decay have spread, after having emigrated from it due to poor living conditions and enduring the pressures of alienation? And what is the advice in this situation?

It is permissible to reside in any country where a Muslim can establish the rituals of his religion and be safe from trials for himself and his family. The best is the country that most assists in obedience to Allah and steadfastness, even if it has a lower salary and standard of living, as long as it meets basic needs. If a Muslim is unable to assess the situation, he should perform Istikhara (prayer for guidance) and consult with scholars and experienced individuals.