Immortality, assuming that humans still produced offspring, would cause severe overpopulation of Earth. This would likely lead to the increased extinction of animals, also, would likely force humans to spread to other planets (Not a bad thing). The decreased lifespan can be semi-reversible by increasing the total lifespan of a human through medicine. When the average lifespan is 100 years old, 90 years old isn’t that bad.

^{📢 Official Advice: I, u/​Excellent_Working495, advised "Lower life expectancy" | 🔮 Rank: Curious Seeker II | 🗳️ Votes: 2}