In version 2.8 it seemed to me that the "stabilize stroke" could be accessed with a hotkey but I'm not sure, in this version 3.1 can a hotkey be configured for "Stabilize Stroke"?, I tried right clicking as before but in the The context menu that opens no longer shows the option "Add Schortcut", is there any other way?
I spent some time searching the Preferences but i couldn't find anything related to the Stabilize Stroke property. As a matter of fact, i couldn't find anything related to Texture Painting. But i found the shortcut by accident which is Shift+S to toggle the Stabilize Stroke property while in Texture Paint mode. Please also note that there is a known issue of this shortcut in this bug report
In version 3.1, this tool_settings.image_paint.brush.use_smooth_stroke already exists but when I use Shift+S, brush tool Smooth is selected.
I solved it by changing in 3dView/Sculpt/Sculpt(Global)/Brush Select, from Shift+S to Ctrl+Shift+S, and now Shift+S to activate Stabilize Stroke worked. (in Sculpt mode).
Open menu Edit ⇾ Preferences ⇾ KeyMap
Then find keymap 3D View ⇾ Image Paint ⇾ Image Paint (Global)
Find the row item Context Toggle with
Shift S shortcut. You can change it here:
If you don't have a context toggle with use_smooth_stroke, you can add a shortcut by clicking the Add New button. Then expand the newly created row item and replace the keyword
wm.context_toggle and input
tool_settings.image_paint.brush.use_smooth_stroke in Context attributes.