Here is a temporary fix you can apply to your dropdowns:
def dropdown_icon_focus_fix(dropdown):
dropdown.selection_field.dom_nodes['anvil-m3-trailing-icon'].addEventListener(
'click', _create_icon_click_func(dropdown)
)
def _create_icon_click_func(dropdown):
def __icon_click(event):
dropdown.selection_field.dom_nodes['anvil-m3-textbox'].focus()
return __icon_click