A consideration that should be made when building dynamic content rules is that rules should be built before uploading the respective content. Dynamic content rules are rules that define what content should be displayed based on subscriber attributes or behaviors. Dynamic content rules should be created before uploading content blocks or images into Content Builder, as they cannot be edited after content is uploaded.References:https://help.salesforce.com/s/articleView?id=sf.mc_ceb_dynamic_content_rules.htm&type=