That cylinder shape around 2 wires covered with plastic looks to me like a
“ ferrite core radio interference suppressor”
similar to the similar cylinders you see on the cord between a keyboard and computer.
It would be good engineering practice to have this ferrite just past the rectifier because the diodes inside the rectifier create little voltage spikes 120 times per second when converting 60 cycle AC to DC.
Was there a larger DC rectifier box between the AC plug and the device shown in your picture?
Palomar Engineers has long sold ferrite “snap on” retrofit kits
https://palomar-engineers.com/ferrite-products/Ferrite-Core-Products-c21312657
