this is a top-level issue to remove the fastpath and/or verify_integrity keyword args from constructors from public interfaces, classes such as Categorical, Series, andMultiIndex. If these are removed all once from a particular class, e.g. Index/MultiIndex for verify_integrity, but are still needed for an internal API, then can add an internal constructor _from_fastpath which can serve instead (e.g. see pandas.core.dtypes.dtype.CategoricalDtype for an example of this) There may be some re-factoring required to keep things DRY.

Most of these will actually need to be deprecated.

• Index (fastpath)
• Index (verify_integrity in subclasses)
• MultiIndex (verify_integrity)
• pd.concat/.append (verify_integrity)
• Series (fastpath) -> DEPR: Series constructor fastpath keyword #55466
• Categorical (fastpath) -> DEPR: Categorical fastpath #52472