React DOM

• Provide a component stack as a second argument to onRecoverableError. (@gnoff in #24591)
• Fix hydrating into document causing a blank page on mismatch. (@gnoff in #24523)
• Fix false positive hydration errors with Suspense. (@gnoff in #24480 and @acdlite in #24532)
• Fix ignored setState in Safari when adding an iframe. (@gaearon in #24459)

React DOM Server

• Pass information about server errors to the client. (@salazarm and @gnoff in #24551 and #24591)
• Allow to provide a reason when aborting the HTML stream. (@gnoff in #24680)
• Eliminate extraneous text separators in the HTML where possible. (@gnoff in #24630)
• Disallow complex children inside <title> elements to match the browser constraints. (@gnoff in #24679)
• Fix buffering in some worker environments by explicitly setting highWaterMark to 0. (@jplhomer in #24641)

Server Components (Experimental)

• Add support for useId() inside Server Components. (@gnoff) in #24172