My fave is Britney. I didn't unstan but when Gaga released her singles from TFM I was really into her. I quickly gave up on her though lol. I re-stanned Britney just before FF and stopped listening to gaga during the btw era because all of the singles were horrible to me, except btw
Beyoncé : Beyhydration '13 and when she left Lemonade on Tidal without releasing it on Itunes for a few hours, I was so pissed
Rihanna : R8. She delivered in the end but that was unbearable
Frank : now, he annoys me
Kanye : when he interrupted Beck, made ignorants remarks and Bey eventually caught the heat because of him
I used to be a big Navy, still am a big fan of Rihanna, but I was really dissapointed she worked with Chris (especially on Birthday Cake) and basically made a huge trainwreck of the TTT era, Now I am over her and actually enjoy the remix but yeah that was one moment.
When her album flopped, she took it the worse way and started doing lame things all over social media
When she started hiring models to marry them, feature them in music videos for the latest album and drop them once the album promo was over just to hire a new one for the next one. That's also when she started using fillers which looked tragic and when she released the atrocity that is Party Queen
but yeah that was one moment.