Use of ES2022 target in v2.??

[CraigMacomber]

Broken API or pattern

Fluid Framework client libraries have officially required ES2022 since 2.0, but did not actually use anything that would break when running in an ES2021 only environment.

We expected to merge #25398, which will start using ES2022 only language (not library) functionality, like private #properties.

Preparation References

Any code compliant with our Client Requirements will be unaffected.

Other code may need to transpile out newer language features.

Packages

All fluid framework client packages will be impacted.

Expected Timeline

Compatibility with older runtimes was officially removed in 2.0, and will be gone in practice in after #25398 is merged.