To filter a "Loaded a page" metric based on the current_url with a wildcard search in Mixpanel, you can use the "contains" operator instead of the exact match ("=") operator. Here's how you can do it:
1. In your Mixpanel report, locate the filter section for your "Loaded a page" event.
2. Look for the "current_url" property in the filter options.
3. Instead of using the "=" (equals) operator, choose the "contains" operator.
4. Enter the common part of the URL you want to match, without the wildcard. In your case, you could use "mysite.com?utm_campain".
This approach will effectively work as a wildcard search, matching any URL that contains the specified string, regardless of what comes before or after it.
It's worth noting that Mixpanel doesn't directly support wildcard searches in the way you've described (using "*"), but the "contains" operator achieves a similar result for your use case.
Remember that the current_url is one of the default properties automatically collected by Mixpanel's JavaScript SDK for web events. It represents "The URL of the page on which the event was tracked."
If you need more advanced filtering options or custom property manipulation, you might want to consider using custom properties or formulas to create more specific metrics based on your URL patterns.
