PowerQueries will evaluate only the first 3,500 characters of the
message field or any other field, so if you report on
max(len(message)), the maximum value it will return is 3,500.
The maximum size of any intermediate table (i.e. output of a
group command) in a PowerQuery is 100,000 rows. If you encounter this limit, consider grouping on a field with less cardinality, or filtering down the result set to produce fewer rows.