Does Campaign Monitor have a text limit?

Campaign Monitor allows you to create text fields on the subscriber list membership object. Each text field has a limit of 250 characters, you can learn more here - https://help.campaignmonitor.com/custom-field-data-types#text

Therefore, syncing long text area fields from Salesforce should be avoided. Anytime a Salesforce field has more than 250 characters, we will be unable to sync it. The Apex Job for ImportListViewBatch or ReportToListBatch will throw an error on the first batch, usually: "First error: Query of LOB fields caused heap usage to exceed limit."