Unkown symbol in schematic
It is a load transient block to assist in testing the stability and capability of the DCDC design

55 seconds into the training video

https://training.ti.com/webenchr-power-designer-simulation-overview?cu=1136926

If you goto the TPS61022 product page ( https://www.ti.com/product/TPS61022# ) there is a WebBench design parameters

Vin  2.7 - 4.35
Vout 5V
Iout 3A



If you were to put them into WebBench, the model for TPS61022 is on the first page and as you can see it is in the base-model. Why this particular design example includes this? Only TI would be able to say. Maybe there is a selling point associated with this part and large step load changes