The part fan boy has omitted
goes a long way toward explaining why VRFB could be considered a loser:
"Development of the project commenced in 2015. Sumitomo has already deployed 37 redox flow battery systems across multiple countries, with a total capacity of 47 MW/162 MWh."
It took them at least 8 years to deploy 162MWh. Compare that to what's going on in the markets right now: "US utility company Xcel Energy has received approval from Minnesota state regulators to build a 1GWh project in the state using Form Energy’s iron-air battery storage technology."
https://www.energy-storage.news/xcel-energy-1gwh-minnesota-project-with-form-energys-iron-air-batteries-approved/
Iron-air is a competitor to VRFB. One of the companies involved is going to build a 1000 MWh project in just one deal! Now compare that to 162MWh in 8 years... Talk about losing out...