Found the solution to this. There were “ in the text which had to be escaped. 

Escaping them with one \ did not work. I’ve seen examples where someone has used \\\ (3 backslashes).

Are 3 backslashes necessary?

Hi there! If the request is being made via API, it’s necessary to escape those apostrophes, like you mentioned. On the user interface it’s ok to send this information the way it is since Pipefy parses the data. Via the API though, this parse has to be manually done by the person/bot that executes the request. 

Long story short, here’s an example of how to correctly input the data in a parsed way:

mutation{
  updateFieldsValues(input:{
    nodeId:12345
    values: {fieldId:"long_text_field123", value:"TEAM CE - Optimize KPI - Volume Mgt - Total Ticket Pool Size Dropped Below 50 Your data has met the Alert Conditions: less than 50.0 Week Ticket Created At matches \"last 7 days\" Report: INPUT: Ticket Pool Size - Total New Tickets by Request Date ( https://eu.holistics.io/dashboards/2199023262493-ce-team/?_e=2199023280138 ) Dashboard: CE Team ( https://eu.holistics.io/dashboards/2199023262493-ce-team ) Here are the records that meet the Alert conditions: (Max 100 rows of results) Week Ticket Created At 2022-09-19 00:00:00.000000 34"}]
  }) {
    clientMutationId
  }
}

(see the “value” parameter)

Thanks @Roberto Chavarria  - appreciate the clear explanation.