The Venus is quite a lot closer to the Sun, though. A few degrees C change in the average temperature of the Earth indeed can cause absolute large changes, potentially killing of most more complex life forms, but even that would be very far off from the point where life is infeasible - especially that the bottom of the ocean won’t be reaching anywhere close to temperatures where proteins denaturate.
Venus gets roughly double the sunlight that earth does, also:
“Conditions possibly favourable for life on Venus have been identified at its cloud layers, with recent research having found indicative, but not convincing, evidence of life on the planet.” https://en.wikipedia.org/wiki/Venus