database read replicas, when do they start hurting more than helping

weve been seeing some performance bottlenecks on our main database, so were considering setting up read replicas. it seems like a no-brainer for scaling reads, but im wondering about the downsides. at what point do the complexities of managing replication lag, ensuring consistency, and handling failover outweigh the benefits of offloading read traffic? curious to hear about your experiences and any strategies you use to mitigate these issues. when did you decide read replicas werent the right move anymore