db.c.insert({a: {b: 1}});
const query = {a: {$lte: {c: 1}}};
db.c.find(query); // Returns a document
db.c.createIndex({"$**": 1})
db.c.find(query); // Doesn't return a document because it tries to use the allPaths index with bounds [{}, {c: 1}]

db.c.drop();
 
assert.commandWorked(db.adminCommand({setParameter: 1, internalQueryAllowAllPathsIndexes: true}));
 
db.c.insert({a: 1});
db.c.insert({a: {b: 1}});
 
assert.commandWorked(db.c.createIndex({"$**":1}));
 
const query = {a: {$in: [1, {b: 1}]}};
printjson(db.c.find(query).toArray());
printjson(db.c.explain("allPlansExecution").find(query).finish());