9.11.3 / 2026-10-21

• fix(update): honor overwriteImmutable in upserts and nested timestamps #16614 #15781 #8619 AbdelrahmanHafez
• fix(model): stop Model.validate() crashing on missing nested objects #16600 NotAFlightRisk
• fix(connection): don't disable autoIndex/autoCreate for a primary ReadPreference instance #16592 NgoQuocViet2001
• docs: remove references to MongoDB versions older than 6.x #16593