TurnItIn has a scheduled maintenance.  This maintenance involves:

• Turnitin and TurnitinUK (including all Integrations)
• Originality (including all Integrations)
• SimCheck (including Integrations)
• Similarity (including Integrations)
• Turnitin Core API (including Integrations)
• Crossref Similarity Check
• Draft Coach
• Revision Assistant
• Canvas Plagiarism Framework
• Integrations through LTI 1.3
• Roster Sync through Turnitin.com
• Feedback Studio for iOS
• iThenticate
• iThenticate (via API)

Additional information can be found on the TurnItIn status page.