Troubleshooting 500 Error with JSON Webhook Payloads

Hey team, I'm using the webhook to receive some JSON stuff. It seems like it cannot accept certain valid JSON payloads even though jsonlint.com validates it's a good JSON payload (and below 1kb). I get a 500 error. Here's a sample of the payload:

{
  "parentKey": "AECH-8",
  "parentTitle": "The AI Stack We Use",
  "parentDesc": "Podcast episode about the AI tools and stack we use",
  "pillar": "{self=https://asianefficiency.atlassian.net/rest/api/2/customFieldOption/100 value=Productivity, id=100}",
  "subtaskKey": "AECH-82",
  "subtaskTitle": "Newsletter",
  "channel": "Newsletter",
  "subtaskDesc": "Thanh AI stack nowadays: \u2028 \tChatGPT Pro \u2028 \tClaude Max \u2028 \tClaude Code \u2028 \tLindy \u2028 \tWispr Flow \u2028 \tAttio (AI first CRM) \u2028 \tTodoist (friendly for AI integrations such as Lindy) \u2028"
}

Hope this can be resolved. I've tried lots of things but boiled it down to the fact that Lindy cannot accept a valid JSON payload. When the "subtaskDesc" is just one sentence, it's fine and works. But as soon as we need to do some encoding, it stops working even though it's valid JSON.