If you haven't already done so, please review and confirm these settings (Property ➝ Tracking Info ➝ Data Retention) as Google Analytics will begin to delete data according to these settings starting May 25.
Impact of this setting as of May 25 is the following:
Any user and event data that is older than your retention setting will be marked for permanent deletion, and will no longer be accessible in Google Analytics.
Deletion will affect the use of segmentation, some custom reports and secondary dimensions when applied in date ranges older than your retention setting.
Reports based on aggregated data will not be affected.