That's becoming cliche so fast it's frightening.
Now, I'm waiting for the same starting block, but then the reincarnated magician is indeed in a future where he has a lot of catching up to do in order to get on par with the new era.
And hopefully that wouldn't be solved by reading books for a couple days.
This can be written in different ways, where some of his problems can addressed with his old knowledge, or he has to learn everything from scratch... His knowledge could be completely outdated, or lost but still relevant, or both the old and new would complement each other leading to creating a whole new style...
There are multiple interesting ways to address this, so why does nobody even try?
Instead, everyone just use the premise as a cheap way to justify the MC being op from chapter one, leading to an overly cliche story.