What is the best way to prevent interference from heatbed cable?  

RE: What is the best way to prevent interference from heatbed cable?

The heatbed cable should always be “floating” behind the heatbed and no part of it should be down below the level of the heatbed no matter where the Y axis is in its travel. If yours is not — disassemble, check to make sure it hasn't been crushed anywhere, and then reassemble it according to the instructions and make sure it is properly secured to both the heatbed and the electronics box. Maybe the cable wrap isn't properly clamped in the heatbed-cable-cover part? That could cause it to be too flexible at that point, allowing it to acquire a downward bend.

Also make sure the cable isn't hitting an object behind the printer.

RE: What is the best way to prevent interference from heatbed cable?

Any mod to prevent the cable from getting stuck below the heatbed or y-axis rod or frame?

RE:

As stated, no mods should be needed. The standard heatbed wiring arrangement does a good job of keeping the wiring out of harms way.

Section 7 of the assembly manual spells it all out with great pictures and illustrations

https://help.prusa3d.com/en/guide/7-heatbed-psu-assembly_172872

RE: What is the best way to prevent interference from heatbed cable?

As others said, if properly wrapped and attached no needs for mods. There are some alternative heatbed covers that make the cable come out at a sideways angle, to avoid collision with the back wall of an enclosure. Just search for, well, "heatbed cover" but they're not intended to lift the cable up in any ways.