cache invalidation in microservices like what do you do

so, like, i'm building a microservices thing and we've hit that super common problem with cache invalidation. we're using Redis for caching, right, but making sure the cache stays the same across all the different services when stuff gets updated? it's a real headache. what are you all doing for updates? like, sending out events, setting TTLs, or some other method? i'm really wondering what works best without making everything way too complicated.