Perhaps because there is a shortage of teff. You might want to look at this article from January, 2021, but it does not provide all the answers.
I personally love injera, but I have not been buying teff for a few years after hearing of this problem. Similar problems may be going in with quinoa, but I have not yet researched that.
I generally stick to things such as wild rice. Of I know where and how it is grown, but that's quite expensive. I try to put my money and my mouth where it makes a difference.
What Are the Domestic and Regional Impacts From Ethiopia's Policy on the Export Ban of Teff?