After updating to CiviCRM 5.27.0 on Drupal, a user reports that pasting large text content in the "Details" box in CiviCase activities cutoff the text. Is anyone else seeing this issue?
The emoji part sounds familiar. If the db tables are not utf8mb4 then emojis get cut off (or fatal error depending on mysql/mariadb/version).
You can convert your db tables to utf8mb4.
In addition you may also want to apply this patch https://patch-diff.githubusercontent.com/raw/civicrm/civicrm-core/pull/17716.patch