To sort of expand on this point, note that the deposit essentially covers two functions
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to cover the costs of paying Kleros jurors in the first round of an eventual dispute over whether the profile should be accepted and
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to provide for a reward to incentivize people to look for potentially inacceptable submissions that would be worth challenging.
Currently, in the first round of Kleros disputes for proof of humanity cases, three jurors are drawn to rule on the case. One way to decrease the ETH deposit required would be to start with initial panels of only a single juror judging these cases. Note that, recalling that Kleros is a Schelling point based system and jurors are incentivized for whether they are coherent with the final juror vote, even starting with only one juror there is still an incentive for that single juror to vote seriously because there is a potential for appeal. So if people think the juror voted incorrectly, there is likely to be an appeal and the first round juror would be rewarded or penalized based on what the appeal jurors decide. So far Kleros has used first round panels of only a single juror for Linguo (https://linguo.kleros.io/).
I would be curious to hear what people think about the idea of starting with one juror panels here. The negatives are that some borderline cases might not be appealed, so there is an added level of variability in terms of whether the first round juror represents how a larger panel would have voted, and that in (the minority of) cases where there is an appeal and you wind up back with a three juror panel anyway, there is an additional delay and some extra gas to have gone through the one juror round.
To illustrate the effect that such a change would have on the deposit size: with current parameters of a .1 ETH challenger reward, a .019 ETH per juror average arbitration fee, and starting with three jurors, we get the current deposit of .1+3*.019=.157 ETH. If one starts with a single juror, that becomes .1+1*.019=.119 ETH. (Furthermore, the challengers don’t have to lock up as much money, so potentially their reward could be reduced somewhat too all else being equal, though the gas they have to pay limits how much that could be reduced.) With the parameters that have been proposed here: KIP-40 Parameter Updates (March 2021) - Votes - Kleros Forum (which adjust for ever rising gas prices), starting with a three juror panel gives .14+3*.028=.224 ETH versus starting with a one juror panel is .168 ETH.