Here's what makes this brutal: Perez wasn't getting slower. His hard tyres were actually stable — degrading at 0.015 seconds per lap, which is fine for Singapore. Verstappen's degradation was technically negative, meaning he was managing the tyres brilliantly, but even if you ignore that, Perez's rubber wasn't the problem.
The problem was pace. Verstappen averaged 96.7-second laps on the hards. Perez averaged 98.2. That's a second and a half, every single lap, for 33 consecutive laps. You don't make that up with fresh tyres or a safety car. You make that up by being faster.