The 'User-provided data collection' in GA4 is a feature that, when enabled, allows for the collection of better conversion data through Enhanced conversions. This feature is particularly useful for those in the Advertising business as it can improve the accuracy of conversion tracking.

Consequences of enabling 'User-provided data collection' for GA4 include:

• It is an IRREVERSIBLE action.
• If you are collecting User IDs in GA4, enabling this option will disable the export of User IDs to Google BigQuery.
• Currently, there is no way to reverse this change once it's been made.

It is suggested to consider waiting before enabling 'User-provided data collection' in GA4 because the feature is still in the beta phase. Enabling it now may lead to downsides such as the inability to export User IDs to Google BigQuery. It might be more beneficial to wait until the function is fully developed and out of the beta phase to avoid such irreversible consequences.