when do you know its time to ditch your monolithic api for microservices

im working on a pretty big app thats served by just one giant API right now. its getting tougher to manage, deploy, and scale different pieces on their own. weve talked about breaking it into microservices, but that feels like a massive job. what are the main signs that tell you its time to actually do it? what problems did you run into when migrating, and what tips would you give someone thinking about this change?