.NET Core also introduced some new CLR features that are incompatible with the CLR used in .NET Framework. Span<T> for example. This has happened before with .

.NET Core also introduced some new CLR features that are incompatible with the CLR used in .NET Framework. Span<T> for example. This has happened before with .NET Framework 2, 3, 4 etc. but instead of making a .NET Framework 5 they rather made .NET Core cross-plattform and threw backwards-compatability-at-all-cost out of the window. While all .NET Framework applications (except the ones that do naughty stuff with reflection) that were compiled for .NET Framework 4.5 behave the same way on .NET 4.8, .NET (Core) got rid of this and lets developers bundle the CLR directly, giving them more leeway for incompatible changes.