Linkfield causes error when filtering in Craft admin

[sgtpenguin]

Kind of an esoteric one, but when filtering for a relations field in the craft admin and choosing "has a value" or "is empty", this error pops up and the search doesn't complete. I filed an issue with Craft and they helped point out that the source of the problem was linkfield.

I did a bit of troubleshooting locally and I think I've narrowed down the issue to craft-utils/src/foreignField/ForeignFieldQueryExtension.php

and specifically line 260. If I swap Json::encode for json_encode it appears to work fine. I couldn't figure out why this might be the case.