Techniques for enabling the identification of anomalous events associated with an object storage service of a cloud provider network using a variational autoencoder model including a pre-trained embedding for selected features of events are described. A variational autoencoder, for example, encodes data into a latent space and reconstructs approximations of the data from an encoding in the latent space. In this context, for example, anomalous events of interest might represent unauthorized or abusive behavior associated with storage resources provided by an object storage service (or in association with other types of computing resources provided by other services of a cloud provider network). Legitimate (or benign) access patterns to an object storage service can be modeled by utilizing observed data plane events stored by an account activity monitoring service. Once trained, the model can be used to identify anomalous events.