Use the “passwords” feature to check if one of yours is compromised. If it shows up, never ever reuse those credentials. They’ll be baked into thousands of botnets etc. and be forevermore part of automated break-in attempts until one randomly succeeds.
They are completely random strings for each site, so having one will not help crack the other.
But if people pick their own passwords, it tends to be some word like you wrote, and then a hacker could try and crack the others by guessing similar words.