1)Super Saiyan Rage: a form exclusive to Trunks which is unlocked when Black blames him for the Zero Mortal Plan over her mother's and girlfriend's (apparent in her case) deaths right in front of him, and allows him to fight SSJR Black on an even ground, thus completely shitting on Goku's and Vegeta's training with an angel just by raging a little ? Calling it stupid is an euphemism.
2)Black's Scythe ability is pretty dumb, but it was acknowledged as such in the series (even Black didn't know how the hell he did that).
3)Vegetto defusing inside Super Boo was already an asspull, though somewhat mitigated by Goku's assumption. Then we learn that the fusion wasn't so permanent after all...why did they decide to tell us about it twenty years later ? How the hell someone who has as much knowledge on the universe as Old Kai didn't know about it, yet Gowasu somehow knows ? The as-a-matter-of-fact way in which this information was delivered nake it sound like it should have been obvious...so all that bullshit about Goku and Vegeta abandonning their identities, their personal lives for the sake of protecting the universe were for absolutely nothing since it was never supposed to be permanent in the first place ? Talk about bad writing.
4)Okay, so Trunks somehow could use the Genki Dama unconsciously even though Goku had to train to use it and ask for people's consent to take their energy ? Dumb enough...then it turns out this Genki Dama, powered up by two half-dead base form Saiyans and 20 weaklings at best, is strong enough to overpower and destroy the physical body of an opponent who could hold his own against Vegetto Blue...da fuck ?
5)Then there is Giygas!Zamasu...I'm pretty sure that a spirit without body isn't supposed to do that. A forced development to force the destruction of Trunks' timeline.
Manga:
6)Zamasu's defusion: so Gattai Zamasu has a time limit supposedly because he usurped the position of a Kaioshin...if the potaras could detect such an usurpation, why does the usurpation even work ? And why is there no way to keep the usurpator from using the time ring ? Kaioshins must be pretty stupid for designing their treasure so badly. But then, there is the whole bullshit about Black and Future Zamasu who are bonded on a cellular level since they're both Zamasu, even though their bodies are completely different, as well as them somehow turning back into Gattai Zamasu and unlocking a broken version of the Kage Bunshin no Jutsu...this is dumb on so many levels.
7)Trunks' healing ability: It's more of a build-up issue, but why Future Shin or Future Kibito had the bright idea to not tell anything about Trunks' ability to heal people, which could have saved many lives ? Why the Kaioshins lose such an handy ability when they graduate from disciples ? Besides, there is a retcon: Toyotaro claimed Trunks unconsciously healed Mai, yet in the chapter proper in which Trunks made a physical contact, she showed no sign of being healed and was still out cold for an entire day.
8)Goku's Hakai: literally comes out of nowhere, since unlike in Anime, Goku wasn't with Beerus when he first used it on panel, yet somehow knows about it. Some build-up could have easily fixed this.
All things considered, I'll settle for Giygas!Zamasu, if only because in addition to being blatantly contrived (no effort was spared to explain how Zamasu is doing that, let alone in such an absurdly large scale), it forced a completely unnecessary ending.