Node added --experimental-strip-types in 22.6.0 and enabled type stripping by default in 22.18.0 and 23.6.0, so node script.ts runs directly. Types are erased and replaced with whitespace; nothing is type checked, so a file with real type errors runs happily. Keep tsc --noEmit in the build for checking.
Erasure only covers syntax that maps one-to-one onto blank space. TypeScript features that emit runtime code are rejected unless --experimental-transform-types is passed: enum, non-declare namespace with runtime members, parameter properties in constructors, and legacy experimental decorators. The error names the construct, for example TypeStripping: enum is not supported.
Import specifiers are not rewritten either. A relative import must name the file that exists on disk, so import './util.ts' works and import './util.js' does not, which is the opposite of what moduleResolution: nodenext demands. TypeScript 5.7 added allowImportingTsExtensions with rewriteRelativeImportExtensions to keep both toolchains happy.