I don't know of any work around with the AGOL map viewer. I assume you have a one to many relationship which is why you see the counts. Configure pop-ups—ArcGIS Online Help | ArcGIS : With a one-to-many relationship, choose to display the related data within the pop-up window or in a table. When displaying attributes within the pop-up, string fields show the count. For numeric fields, you can choose to display the sum, min, max, average, or count. Depending on your work case you might find this helpful. Related Tables – Exploring New Ways to use Collector for ArcGIS
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