Yes this is a UK site so this advice only pertains to the UK versions of these seats.
In the UK the Graco Turn2Me and Joie 360 don't have an anti-rebound bar, although the newer seat Joie i-Pivot does. There are also some other brands which don't, e.g. Cosatto don't have one on all of their seats. Essentially the high base and the tilt on it provide some of the anti-rebound protection, as does the support leg (I don't think US spec seats tend to have support legs, as I understand there is no floor on the FMVSS 213 testing rig so they have to pass without one.)
With some models like the Cosatto they have to be in the most reclined position when rear facing, if that's the case then it probably provides an anti-rebound function, so it must be followed.
PESRI crash test seats for Latin America and the Caribbean and they have some really clear videos so you can compare Joie 360 Spin with a similar (European spec) model like Britax Dualfix which has a rebound bar. Neither seat rebounds too badly because they both have a support leg. But you can see that the lack of rebound bar on the Joie does mean that it rebounds significantly more than the Britax.
n.b. when watching these videos, ignore what the dummy's legs are doing as they are not articulated like real legs, just weighted. Look at how much the seat lifts up after the initial crash phase (this is the rebound) and the movement of the dummy's head/torso. You can see although it moves a lot more in the Joie seat, it doesn't hit the back of the vehicle seat.
Joie i-Spin 360:
Britax Dualfix i-Size:
Then this video shows a direct comparison between seats which do and don't have the support leg. All the major European spin seats have this, so it's a more relevant comparison if you're in the US.
I don't know anything specific about the North American models, so if those are the seats you want to ask about, you'd be best off finding a CPST forum as they are the North American car seat nerds 