[2020] How do I fix this?

You will pretty much have to rebalance your city. The number of people living in your city, the number of jobs, the amount of goods they use and the amount of trash they produce are all things that the mod affects, and so those numbers have shifted. Most likely your population and jobs doesn't line up anymore, and your city's garbage facilities might not be able to handle the unmodded garbage production.

While you can remove the mod from a city, it generally isn't recommended as it causes a mess like this. But if you are alright with having to rebalance everything, then it is possible. It just takes some time and figuring out your city's new needs. And hopefully your city has enough money to handle the transition. :)