Hmm...  Looks like a unified diff to me...
The text leading up to this was:
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|diff --color -up st-0.8.4/config.def.h st-0.8.4-modified/config.def.h
|--- st-0.8.4/config.def.h	2020-06-19 14:59:45.000000000 +0530
|+++ st-0.8.4-modified/config.def.h	2021-07-09 19:31:14.512632819 +0530
--------------------------
Patching file config.def.h using Plan A...
Hunk #1 succeeded at 85 (offset -11 lines).
Hunk #2 succeeded at 121 (offset -11 lines).
done