Time-based workflows are a type of workflow that execute actions based on a specific time trigger, such as a certain number of days before or after a date field on a record. Time-based workflows can cause delays in processing because they are added to a queue and processed in one-hour batches. If the queue is large or the system is busy, the actions may not execute at the exact time they are scheduled. Therefore, time-based workflows can contribute to reaching the hourly limit for processing workflow time triggers. References:
https://help.salesforce.com/s/articleView?id=sf.workflow_time_action_considerations.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.workflow_limits.htm&type=5