Hmm...  Looks like a unified diff to me...
The text leading up to this was:
--------------------------
|diff -up st/config.def.h st-gradient/config.def.h
|--- st/config.def.h	2021-01-12 03:24:27.313995808 +0530
|+++ st-gradient/config.def.h	2021-01-12 03:03:37.837696991 +0530
--------------------------
Patching file config.def.h using Plan A...
Hunk #1 failed at 95.
1 out of 1 hunks failed
Hmm...  The next patch looks like a unified diff to me...
The text leading up to this was:
--------------------------
|Common subdirectories: st/.git and st-gradient/.git
|diff -up st/x.c st-gradient/x.c
|--- st/x.c	2021-01-12 03:24:27.313995808 +0530
|+++ st-gradient/x.c	2021-01-12 03:08:40.850694072 +0530
--------------------------
Patching file x.c using Plan A...
Hunk #1 succeeded at 1430 (offset -18 lines).
done