The Sentry Ingestion Domains Updates involve changes to improve security and performance by disabling non-encrypted HTTP ingestion, updating DNS A records for sentry.io and app.getsentry.com, and recommending the use of organization subdomains for event ingestion. The changes are intended to increase overall security and performance using modern protocols like TLS 1.3, HTTP/2, and HTTP/3, resulting in lower TTFB times globally due to Anycast technology. The updates will be rolled out on September 1st, 2023, with a series of brownouts starting from July 3 through August 31 to allow customers to make necessary changes to their network configurations.