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In particular, Ireland is concerned that crypto donations can conceal the identity of a donor and increase the likelihood of dark money entering campaigns via foreign governments.
This is the biggest concern that I think the Irish government is afraid of. This decision is not welcome, but it is entirely reasonable that Ireland has made the right decision.
If political donations are used in cryptocurrency, it will be very difficult to control the amount of dark money that is brought in to disrupt or interfere with election campaigns. This is simply a decision intended to prevent foreign organizations from meddling in a country's political apparatus.