Editing event participant can affect wrong record if multiple participants are opened in multiple tabs/windows
This is an old issue (sorry I couldn't yet find the original issue in JIRA that was raised for this.)
It was recently attempted to get fixed here: #1164 / https://github.com/civicrm/civicrm-core/pull/14244 but a regression caused the patch for event participants to be reverted.
The problem, example of dmaster:
- Events > Find participants > Search
- 'Edit' one participant (Lincoln) in a new tab
- 'Edit' a second participant (Teresa) in a new tab
- Go to Lincoln's edit tab, change to no-show, save
- The change has been applied to the WRONG record (Event registration information for Teresa Terry has been updated.)
This is because the participant ID is being stored in the session.