There is a general document about shoot maintenance that you might want to read. Here, we describe how you can influence certain operations that happen during a shoot maintenance.
As outlined in above linked document, Gardener offers to restart certain control plane controllers running in the seed during a shoot maintenance.
Extension controllers can extend the amount of pods being affected by these restarts.
If your Gardener extension manages pods of a shoot's control plane (shoot namespace in seed) and it could potentially profit from a regular restart please consider labeling it with maintenance.gardener.cloud/restart=true.