Kubernetes' .spec.revisionHistoryLimit is used in keeping track of changes to the Deployment definition. Since these definitions are small yaml files, it doesn't seem like much (given the typical conditions of a modern cloud server) to keep 100's or more of these definitions around if necessary.
According to the documentation, it is going to be set to 2 (instead of unlimited). Why is this?
Keeping it unlimited would eventually clog up etcd and iiuc etcd isn't designed for big data usages. Also the Kubernetes control plane is syncing and downloading regulary, which means there would be much unnecessary data to process. Just image service with daily deploymets, which runs over a year.
And setting this to a high-ish number like 100 seems very random to me. Why not 1000 vor 9001? Besides that I cannot imaging anyone who might want to roll back something a hundred versions.
Anyway, we are only talking about a default setting, so you can set it to a very high number, if your usw case requires it.