Yes, the algorithm is breakable with a few examples to figure out the base word and the pattern. But this requires human attention at your personal algorithm.

Yes, the algorithm is breakable with a few examples to figure out the base word and the pattern. But this requires human attention at your personal algorithm. Unless you are enough of a celebrity or public figure to be personally targeted, nobody will bother. A password leak is going to have 100 million accounts in it, at least 50% of these reused without modification at other websites. Any automated bots and spammers will just try the exact passwords on other sites. If it doesn't work, they move on to the next account and password, instead of trying to guess modifications of non-working passwords.