Hello, I am at 11:15 and my bevel creates this weird shape( only on those corners top and bottom)
I don't know why, but so far everything has gone smoothly.
Hi Irina iirina.yuko ,
That looks suspiciously like so-called 'double Vertices'.
Select all (with A) in Edit Mode and M > Merge > By Distance. For good measure, follow that with the SHIFT+N hotkey combo, to re-caclulate your (or, to be more precise, the Normals of your Mesh).