External SSD causes "Accessory needs more power" when plugged into M1 iMac with external Thunderbolt monitor

I have a new M1 iMac with **two Thunderbolt ports**. I want to use one to control a small external monitor, and the other to run a very fast **external SSD**. I was very disappointed to find that **when the monitor is plugged in**, I can't use the SSD. I get the warning: > **Accessory needs more power** Disconnecting other accessories may allow this to work. I suppose that this is a limitation of the M1 Macs, but it pretty much renders one of the Thunderbolt ports useless. Is there any way to use both for what seems like a pretty normal use case (SSD + monitor)?