What's the root cause to wiki's recommendation: "Pause consumption when add a new column"?

In the ingestion transformation wiki page, it mentioned that

If a new column is added to table or schema configuration during ingestion, incorrect data may appear in the consuming segment.

To ensure accurate values are reloaded, do the following: Pause consumption (and wait for pause status success)

Is it only limited to table which has ingestion transform config? If not, it seems a breaking change since we need to pause consumption for every schema update.

Another question: In which scenario the data will incorrectly appears?