Why exactly does this matter?
I don't think the ChipMixer signing address was supposed to be funded. My guess is someone send their coins to that address by mistake.
They'd have done that after mixing their coins though.
I followed one of the chains and it brought me here:
https://www.blockchain.com/btc/address/18HecYpFRs4s54oiLKnXLpfzFUb1VFQMvt - maybe it was a small chip, they liked the service and wanted to donate?