Use true instead of yes.

tasks/workstation/freebsd/software/gnome.yml

@@ -2,7 +2,7 @@
 # Provide FreeBSD with a DE.
 
 - name: Workstation | FreeBSD | Software | GUI | Install UI Components
-  package: 
+  package:
     name:
     - xorg
     - gnome3-lite
@@ -25,8 +25,8 @@
       gnome_enable="YES"
       #gdm_enable="YES"
       lightdm_enable="YES"
-    create: yes
-    backup: yes
+    create: true
+    backup: true
 
 - name: Workstation | FreeBSD | Software | GUI | Create fstab Entries
   blockinfile:
@@ -35,7 +35,7 @@
       proc            /proc           procfs  rw      0       0
     marker: '# {mark} MANAGED BY ANSIBLE | GNOME Components'
     state: present
-    backup: yes
+    backup: true
 
 - name: Workstation | FreeBSD | Software | GUI | Mount All
   shell: mount -a