Yes, N8N_VERSION_NOTIFICATIONS_ENABLED is totally unrelated to that.
I guess the problem is that you did cancel the migration process in the middle of it. Now you seem to have this temp-database with already some data in it and this causes problems. So if you have a database management tool like https://dbeaver.io/ you can open the sqlite database file (can be found under ~/.n8n/database.sqlite) and then delete the database temporary_execution_entity manually and then start n8n again.