When copying a survey, survey-level plugin settings (stored in lime_plugin_settings with model = 'Survey') are no longer transferred to the copied survey. The copy receives default values instead of the settings configured on the original survey.
This is probably a regression. The behaviour was working correctly in LimeSurvey 6.1.3: copying a survey correctly duplicated all survey-level plugin settings to the new survey ID. In current versions of LimeSurvey 6 the copied survey shows only plugin default values.

This can cause serious issues to many users relying on automated work-flows by creating survey copies. We know at least 5-6 customers alone which have tools in place to copy surveys with important plugin settings e.g. for course evaluation or project status surveys. With the plugin settings broken, work-flows like email sending or other plugin related features are fully broken.

AI generated code details:
Support for copying plugin settings was originally introduced in October 2017 via commit cfbe597, which resolved feature request 09235. The implementation works by including a <plugin_settings> block in the XML export of a survey (surveyGetXMLStructure() in application/helpers/export_helper.php) and re-importing it under the new survey ID (XMLImportSurvey() in application/helpers/admin/import_helper.php).
Starting with LimeSurvey 6.14, the survey copy workflow was refactored: the dedicated Copy tab was removed and replaced by a modal dialog. It is suspected that the $exclude parameter passed to surveyGetXMLStructure() during the copy operation now includes plugin_settings, or that the new code path bypasses the plugin settings export/import entirely. The export code itself (export_helper.php) still contains the plugin settings query and has not been removed.
Verification of the regression can be done by checking whether lime_plugin_settings receives any rows for the new survey ID after copying.