There was a fiat-denominated cap in an early version of [what became] Matt Luongo’s ZIP 1011. I replied on the thread about that, saying that I wasn’t sure ECC would be able to serve effectively in that role: Decentralizing the Dev Fee - #83 by zooko
Matt subsequently removed that provision from his ZIP before the community sentiment collection. At the time of the community sentiment collection, [the proposal that became] ZIP 1011 no longer included a fiat-denominated cap:
[Edited by @daira to correct the ZIP number.]