The yellow floatation devices are used to provide extra buoyancy and stability to disabled vehicles while they are being towed. The first image shows tow lines being hitched to the disabled vehicle.
Allegedly a new airborne IFV prototype... This looks different from a previously photographed airborne IFV prototype. Could be a private effort or a competitor or maybe a related evolution.
I noticed for the new ZBD prototype we've been seeing, there seems to be different versions. If you compare picture 1 and picture 3/4 in this tweet, you will notice the headlamp arrangements are different as well as the ERA/armor plate arrangement.