Another theory is that a large holder switched to Monero, or simply makes usage of this internal function as a mixer. eXch is really attractive for an anonymous entity. No KYC and supports Tor. It reduces some risks of de-anonymization by just sending and receiving bitcoin via Tor Browser, than to use a less reviewed, more complicated software like Bisq. (And it might be cheaper as well)
Something is definitely happening with monero that is affecting all exchanges, and fee for monero remans around 5% on eXch.
Or maybe it's because of the new EU AML regulations and the announcement of the ban and restrictions on privacy coins and self-custody wallet payments. Although, strangely, this kind of reaction came already based on the announcement.
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