With Google Signals you can enable cross-device reporting and remarketing
The big downside of enabling Google Signals can be that your reports in GA4 have thresholds.
These thresholds are being activated because otherwise, advertisers could maybe identify individual users based on the extra data.
The big pros of Signals are that you get extra insights into demographics, you can make remarketing lists, have Cross-platform reporting, and have more advertising reporting features.
If you are not interested in these extras you should not activate this tool.
If you want to use this tool and have no thresholds you could export data to Big Query.
Big Query can’t work with Google Signals so the data will not contain thresholds.
One other option to see data without thresholds is changing the default reporting identity to device-based!