eventstats is not available after an aggregation

[kortemik]

Describe the bug
eventstats is not available after an aggregation

%dpl

index=search_bench earliest=-5y
| timechart span=1d count as CNT
| eventstats max(CNT) as maxCNT

results into

[WRITE_STREAM_NOT_ALLOWED] `writeStream` can be called only on streaming Dataset/DataFrame.

Expected behavior
should work

How to reproduce
use the provided query

Screenshots

Software version
pth_07 8.1.1

Desktop (please complete the following information if relevant):

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Additional context