tl;dr: "...will probably freeze to death...before it runs out of power..." If power keeps it from freezing to death and it hasn't run out of power, why would it freeze to death?
Space.com's NASA's Perseverance rover is the 1st spacecraft in years to carry fresh US plutonium. It won't be the last. includes the following passage:
So, if you want to send a spacecraft to our solar system's giant planets and beyond, or to other dark places like the permanently dark regions deep in craters near the moon's poles, you'll likely want nuclear power. That preference isn't just about sunlight either; nuclear power also helps spacecraft confront threats like low temperatures and high radiation.
"It allows us to explore where the sunlight doesn't get, but it also allows us to explore harsh environments, and that's because we can take our heat with us," June Zakrajsek, the Radioisotope Power Systems (RPS) program manager for NASA at the Glenn Research Center in Ohio, told Space.com. "It's the reliability and those kinds of factors that are really important for our missions, and we couldn't do some of the missions without it."
NASA's next plutonium-powered spacecraft will be the Dragonfly rotorcraft mission, launching in 2027 to Saturn's strange moon Titan, which NASA says receives about 1% of the sunlight that Earth does. Because of Dragonfly's nuclear power source, the spacecraft will probably freeze to death in the landscape of liquid methane and towering water-ice cliffs long before it runs out of power, Zakrajsek said.
Question: Why would Dragonfly freeze to death at all? All missions come to an end and for some reason, something breaks or solar panels get covered in dust or money runs out and administrators pull the plug, but coming from a NASA program manager this sounds so incredibly certain. Is there a plan to "freeze it to death" on purpose?