Future Trunks' Strength

First of all do we need to make clear at which level of power Trunks' current enemies (and allies) operate.
Goku and Vegeta both need to use SSJ-Blue to keep up with Zamazu and Gokue Black (no matter if transformed or not)
SSJ-Blue is the Super Saiyan version of SSJ-Red/SSJ-God; thus a form that surpasses SSJ-Red/-God by a lot.
Goku was able to force Beerus to use ~70% of his power when he used SSJ-Red/-God against him. Thus should SSJ-Blue roughly equal Beerus power or at least close that gap by a lot.
This is the level where Goku Black and Zamazu move, roughly around that of Beerus.

Now is there the fact that Goku not only needed a lot more power to beat Beerus, as Goku estimated that not even Vegetto (who easily toyed with Buu's strongest form) would be capable of actually harming Beerus, but also Godly Ki, as you can't use the mortals Ki to actually harm a god.

If Zamazu and Black Goku are gods or not is up to speculation.
Both are Kaioshin who could canoncially get hurt by mere mortals, despite them being labaled as gods. Yet are they also capable to go up against enemies who use Godly Ki, meaning that they themself must possess it.
Yet, no matter if they are gods or not, is their strenght vastly superior to that of the strongest mortal ever introduced.

Trunks simply surpasses this strenght for absolutely no reason and he does not have Godly Ki. He didn't even train in any way since he fled to the past and seeked their help, except for that one scene with Vegeta and his strength comparision with Goku, but I wouldn't call that training.
You could argue that he got Godly Ki thanks to all his encounters with Black, his training with the Kaioshin and him being around Goku, Vegeta, Beerus and Whis for several days and that their Ki somehow started to effect his, but if this is the case, then many other characters should've gotten stronger by simply being around these characters as well and not only Future Trunks.

Thus does it not make sense that Future Trunks surpassed Vegetto, without being properly made into a god and neither that he is able to surpass the power of Goku, Vegeta, Goku Black and Zamazu without any kind of training.