We observed this failure here. I spent some time minimizing the repro so that it runs faster but didn't look into it deeply. See attached file query_fuzzer_repro.js

The problematic find command is:

    {
        find: 'fuzzer_coll',
        filter: {'obj.obj.obj.array': {$exists: false}},
        projection: {'obj.obj.obj.num': 0},
        sort: {'obj.obj.obj.obj.obj.array': 1, _id: 1}
    },

However, the fuzzer code will augment the projection with a $meta:"sortKey" expression. As a result, the find command runs in the classic engine, but the equivalent aggregate command runs using SBE. The find/classic version returns 102 documents whereas the agg/SBE version returns just 1. The following indexes exist on the collection, which I've found is necessary for the repro:

const indexList = [
    {
        'obj.obj.obj.array': 1,
        'obj.obj.obj.obj.date': -1,
        'obj.obj.num': -1,
    },  // 15
    {
        'obj.obj.obj.array': 1,
        'obj.obj.num': -1,
    },  // 77
];

It's possible that this is related in some way to SERVER-56132, since it looks like this failure also could involve early exit during SBE multi-planning.