this is not so much related to the project but I noticed that in 4.3 version, when having an armature selected, in edit mode, the proportional edit button disappears. it does show if I have a mesh selected in edit and object mode. just curious if blender took off proportional edit button when editing bones in 4.3
Spikey is correct.
Armatures don't support proportional editing, so it was removed in accordance to their design philosophy. (only show relevant options)
Some things like that have been in Blender for so long that they become invisible.
I didn't even notice the button was there, let alone that it disappeared haha