Today I told to my Project Manager that after one year of taking care ( explaining thousands of lines of codes) to an external team ( another company) to migrate our application from a monolith to microservices + react, that the React UI they build looks like shit.

He replied "at least it works".

Now I must find the courage to tell him that it doesn't work correctly because instead of a simple *migration* the external team rewrote some algorithms used in a bank application and now the data are wrong.

advices ?