I've had good results with Castelli Velo vest. No longer made, but may still be out there.
Super light, not flappy, & stuffs into it's own little pocket, down to the size of an inner tube.
Not a Castelli fan overall, but this has worked.
Better without pockets IMO as you want to take off & stow it later, so no point in moving the pocket stuff,
and vests with pockets stuff to a larger size- taking up a whole jersey pocket.