PowerQueries will evaluate only the first 3,500 characters of the
message field, so if you report on
max(len(message)), the maximum value it will return is 3,500. All fields parsed during ingestion are available in PowerQueries (even if the parsed fields occur beyond the 3,500 character mark).
The output of a PowerQuery is a maximum of 20,000 rows. This is applies to aggregation and returned rows. This limit can be raised on request.