### Fixed
* Modified the behavior of `Array.insertManyAt` to return a copy of the original array when inserting an empty array. ([PR #18353](https://github.com/dotnet/fsharp/pull/18353))

### Added
* Added nullability annotations to `.Using` builder method for `async` and `task` builders ([PR #18292](https://github.com/dotnet/fsharp/pull/18292))
* Support for `and!` in `TaskBuilder` ([LanguageSuggestion #1363](https://github.com/fsharp/fslang-suggestions/issues/1363), [PR #18451](https://github.com/dotnet/fsharp/pull/18451))

### Changed

### Breaking Changes
* Struct unions with overlapping fields now generate mappings needed for reading via reflection ([Issue #18121](https://github.com/dotnet/fsharp/issues/17797), [PR #18274](https://github.com/dotnet/fsharp/pull/18274)). Previous versions of FSharp.Core returned incomplete mapping between fields and cases, these older fslib versions will now report an exception.
