Hmm...  Looks like a unified diff to me...
The text leading up to this was:
--------------------------
|diff -up dwm-6.5_winview+gaplessgrid/config.def.h dwm-6.5_gridall/config.def.h
|--- dwm-6.5_winview+gaplessgrid/config.def.h	2025-06-13 08:46:42.388851558 -0300
|+++ dwm-6.5_gridall/config.def.h	2025-06-13 08:50:53.706890303 -0300
--------------------------
Patching file config.def.h using Plan A...
Hunk #1 failed at 98.
1 out of 1 hunks failed
Hmm...  The next patch looks like a unified diff to me...
The text leading up to this was:
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|diff -up dwm-6.5_winview+gaplessgrid/dwm.c dwm-6.5_gridall/dwm.c
|--- dwm-6.5_winview+gaplessgrid/dwm.c	2025-06-13 08:55:19.724867025 -0300
|+++ dwm-6.5_gridall/dwm.c	2025-06-13 08:49:14.708874297 -0300
--------------------------
Patching file dwm.c using Plan A...
Hunk #1 succeeded at 233 (offset -1 lines).
Hunk #2 succeeded at 2095 with fuzz 1 (offset -20 lines).
done