"formatted_body" is set to "* (null)" when editing messages

[progval]

Steps to reproduce

1. Send Edit as a message
2. Rewrite it as Edit 2

Outcome

What did you expect?

It should send "* Edit 2" as the value of "formatted_body'

What happened instead?

It sends "* (null)" as the value of "formatted_body'

Here is the whole event:

{
  "content": {
    "body": "* Edit 2",
    "format": "org.matrix.custom.html",
    "formatted_body": "* (null)",
    "m.new_content": {
      "body": "Edit 2",
      "msgtype": "m.text"
    },
    "m.relates_to": {
      "event_id": "$SNcTFgRqjHARfq8FMDgYPGn9CFGRyPMNwDJax3sIIyc",
      "rel_type": "m.replace"
    },
    "msgtype": "m.text"
  },
  "origin_server_ts": 1658148449393,
  "sender": "<redacted>",
  "type": "m.room.message",
  "unsigned": {},
  "event_id": "$uZkqokz323-rN0GzVLxGDxB7aLzLCGRFzzFqbAdO-1o",
  "room_id": "<redacted>"
}

Your phone model

Element 1.8.20

Operating system version

No response

Application version

No response

Homeserver

synapse 1.62.0

Will you send logs?

No