Bug Report
Please answer these questions before submitting your issue. Thanks!
1. Minimal reproduce step (Required)
SELECT JSON_EXTRACT('{"properties": {"$type": "TiDB"}}','$.properties.$type')
2. What did you expect to see? (Required)
"TiDB"
3. What did you see instead (Required)
{"$type": "TiDB"}
4. What is your TiDB version? (Required)
5.7.25-TiDB-v5.1.0