Which action should be avoided in a loop within a flow?

In a loop within a flow, updating multiple records should be approached with caution because it can lead to performance issues and exceed platform limits. When a flow processes records in a loop, each iteration can trigger record updates, and if there are many records to process, it can result in hitting governor limits, which Salesforce applies to ensure fair use of shared resources.

Salesforce has certain limitations on the number of DML operations (like updates) that can occur within a single transaction. When you perform updates inside a loop, you're executing a potentially high number of DML operations, which can quickly accumulate and cause the flow to fail at runtime due to these limits.

On the other hand, creating new records, executing a single action, and assigning variable values are generally manageable within a loop structure, provided that each action is executed within the governor limits. Creating new records can be batched outside the loop to avoid performance issues, and both executing single actions and assigning values are typically low-impact operations that can be performed without significant risk of exceeding limits.