Mysterious DynamicSupervisor child shutdown

Hi, I have a DynamicSupervisor spawning 20 child processes. They work fine for a few minutes, and then all of them terminate unexpectedly. The supervisor doesn’t restart the processes even though I have the restart option set to :permanent. I’ve trapped exits of the child process, and indeed the terminate callback is receiving a :shutdown message. None of my code could potentially be shutting down the child processes, let alone all 20 of them simultaneously. All other GenServers are untouched, the parent process keeps running.

What could be causing such weird behaviour, and how can I get the DynamicSupervisor to restart its children?

The application is database-heavy, the workers constantly write to the database, hundreds inserts per second each. Perhaps this is somehow related? The child processes interact directly with Ecto with no intermediary processes.

defmodule App.Worker do
  use GenServer, restart: :permanent
  def start_link(args), do: GenServer.start_link(__MODULE__, args)

  def start_new_worker() do
    {:ok, pid} =
      DynamicSupervisor.start_child(
        App.WorkerSupervisor,
        {__MODULE__, :no_args}
      )

    pid
  end

  @impl true
  def terminate(reason, state) do
    Logger.info("worker terminating, reason: #{inspect reason}")
  end
end

application.ex:

defmodule App.Application do
  use Application

  def start(_type, _args) do
    children = [
      {DynamicSupervisor,
       name: App.WorkerSupervisor, strategy: :one_for_one}
    ]

    opts = [strategy: :one_for_one, name: App.Supervisor]
    Supervisor.start_link(children, opts)
  end
end

Thank you!