The official Roblox description says players hatch eggs to collect rare pets and earn money from pets. The available sources do not provide a fixed income table, weight rule or universal mutation bonus.
Read the current value
If the live experience displays an individual pet's income, record the pet name, displayed value, mutation, any visible weight and the observation date. Compare like with like, and do not turn one observation into a universal rate.
Why fixed tier lists go stale
An observed pet value does not prove a fixed multiplier for every pet. A useful tier list needs a date, game version and test notes rather than only a ranking image.
For now, use the live experience as the source of truth for any displayed income and keep unverified Index or weight claims out of a ranking.