This message is usually displayed when there's lots of data in your account, and you are trying to view too much at the same time. Remember, Funnel is a monthly Subscription, especially when viewed from a Consumption standpoint.
Funnel can process up to 100,000 rows per query in the Data Explorer; if the number of rows exceeds this threshold, the "Too many rows, try using a shorter date range or fewer dimensions." This is an error message returned by Funnel, which indicates that the query would result in too many rows and was therefore aborted. Funnel does this for performance reasons and to avoid sending huge or incomplete responses.
There are a few different things you can do to handle this situation, but more or less, it all boils down to reducing the cardinality of the data returned.
The simplest way to do this is to reduce the segmentation in your query, i.e., by removing a dimension or a filter. Time series widgets will always include the Date dimension, which means that if a time series widget fails to load, you can either reduce the time span or use another type of widget that displays the totals for the request period.
From a practical standpoint, these issues are a dependency on Funnel's offerings and are in no way tied back to Power BI or a related service.
