No issues at all for low voltage DC systems using low voltage DC contactors. They were designed for it, and raising voltage while decreasing amps should be fine. Both voltage an current affect DC arcing so if you are in the voltage range the device was designed for, at lower current, all is well.
It is a different matter for higher voltage DC at moderate currents, the arc length can be quite long, making current interruption a challenge. The relay products designed for it often use permanent magnets to bend the arc to a longer path, and multiple contacts to increase total arc length so the arc on opening will extinguish.
I've blown lots of switches, breakers and contactors messing with my nominal 120VDC (up to 156V). My home and shop are 120VDC powered, with the shop also having generator or inverter AC. I used Cooper brand switches that were rated for 150VDC in my house, but those are no longer available. The Leviton rotary light switches date back to Edison's (110VDC) time in design, and I've tested them for hundreds of cycles switching 4 amps, and only use them for 1 amp.