There are many temporary toggles that have been in the Open edX platform for years, and have not yet been removed.
First search for open DEPR tickets.
If none are available, search openedx in Github for "toggle_use_cases: temporary" for old temporary toggle that can possibly be deprecated.
See the Project board READMEs for help creating DEPR tickets.
Once https://github.com/openedx/edx-toggles/issues/284 is implemented, the instructions/link to search for temporary toggles needs to be updated.
Reach out in Slack in #wg-depr-slash-n-burn with any questions, or to join the DEPR WG meetings.