Log Analytics workspace:TimeGenerated value Current time for less than 48hrs logs(From current time)

Azure Monitor enforces strict rules for the TimeGenerated field values cannot be more than two days old at ingestion or more than one day in the future. If logs fall outside this window, Azure Monitor automatically replaces the timestamp with the actual ingestion time. This explains why your logs with TimeGenerated less than 48 hours from the current time are accepted, but older values are reset.

https://learn.microsoft.com/en-us/azure/azure-monitor/logs/log-standard-columns