I took up on a very badly maintained project. You could see that the devs never talked to each other: there was repeated code everywhere, mixingCamelCase with_snake_case, functions that did two very different things and two functions that did almost the exact same. The frameworks being used were a couple of years old (jQuery and its crew) but we wanted to migrate to the more modern ones (Vue and its crew). Instead of nice row-based aggregates in SQL, they preferred to loop through the response and firing up N^2 SQL requests. On top of that, the company was changing its target market, so we wanted to make the code more abstract to fit different customers. To reflect this, they wanted to change the names of the core models.

Oh and did I say that I was the only competent dev in charge of this? The rest were interns.