Hi @lynsey_crew and welcome back to the Community!
The following Community thread answered by my colleague explains an important distinction between the different types of Shopify tags that are utilized by Klaviyo:
I’d recommend reviewing that thread in order to better understand why some tags may behave differently, and then additionally our Help Center Article on Shopify tag filtering:
How to use Shopify tags to filter customers
While you can use Klaviyo to segment and filter customers with Shopify tags, the actual Shopify tag creation and management is performed in Shopify. I did find this Shopify Help Center Article on the topic, but any further investigation on that side would have to go through Shopify support:
https://help.shopify.com/en/manual/shopify-admin/productivity-tools/using-tags
I hope this helps, and thanks for using the Community!
-Brian