Is spying on others and thinking badly of them haram?

Haram Speech & character Quran · 1

Short answer

Yes. The Quran tells believers to avoid much suspicion because some suspicion is sinful, and not to spy on one another (49:12). Searching for people's faults and secrets is forbidden.

Evidence

Quran

يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ ٱجْتَنِبُوا۟ كَثِيرًۭا مِّنَ ٱلظَّنِّ إِنَّ بَعْضَ ٱلظَّنِّ إِثْمٌۭ ۖ وَلَا تَجَسَّسُوا۟ وَلَا يَغْتَب بَّعْضُكُم بَعْضًا ۚ أَيُحِبُّ أَحَدُكُمْ أَن يَأْكُلَ لَحْمَ أَخِيهِ مَيْتًۭا فَكَرِهْتُمُوهُ ۚ وَٱتَّقُوا۟ ٱللَّهَ ۚ إِنَّ ٱللَّهَ تَوَّابٌۭ رَّحِيمٌۭ ﴿١٢﴾

O ye who believe! Shun much suspicion; for lo! some suspicion is a crime. And spy not, neither backbite one another. Would one of you love to eat the flesh of his dead brother? Ye abhor that (so abhor the other)! And keep your duty (to Allah). Lo! Allah is Relenting, Merciful.

This is general information, not a fatwa. For your own situation, ask a qualified scholar.