Good to see, I've been looking forward to this being explained for ages
That article was way too long so for those that are already familiar with the Pioneer spacecraft and the anomaly I'll just paste here the one paragraph from it that presents their conclusion:
"The team found that a good half of the force came from heat from the RTGs, which bounced off the back of the spacecraft antenna. The other half came from electrical heat from circuitry in the heart of the spacecraft. Most of that heat was radiated through louvers at the back of the probes, which weren’t as well insulated as the rest of their bodies, further contributing to the deceleration."