Thanks, I couldn’t spot a license on the website, but existence of an arch package does probably mean the license is okayish.
But alright, I realized you must download the archive to find LICENSE.md in there: https://github.com/be5invis/Iosevka/archive/refs/tags/v34.9....
The license is "SIL Open Font License, Version 1.1." from http://scripts.sil.org/OFL