Here's a summary of what's new in F# in this preview release:
Note: Release notes for F# are generated for all contributions to the dotnet/fsharp repository and split across language, library and compiler changes.
Release notes for new F# language features list language changes that have to be enabled by <LangVersion>preview</LangVersion> project property in .fsproj project file. They will become the default with .NET 10 release.
Changes to the FSharp.Core standard library are applied automatically to projects compiled with new SDK, unless they pin down a lower FSharp.Core version.
General improvements and bugfixes in the compiler implementation are at Release notes for FSharp.Compiler.Service.