{% macro avatar(user_id=None, css_style=None) %}
{% set user_info = frappe.utils.get_user_info_for_avatar(user_id) %}
<span class="avatar avatar-small" title="{{ user_info.name }}" style="{{ css_style or '' }}">
	{% if user_info.image  %}
	<img
		class="avatar-frame standard-image"
		src="{{ user_info.image }}"
		title="{{ user_info.name }}">
	</span>
	{% else %}
	<span
		class="avatar-frame standard-image"
		title="{{ user_info.name }}">
		{{ user_info.name[:1] }}
	</span>
	{% endif %}
</span>
{% endmacro %}
{% macro avatar(user_id=None, css_style=None) %}
{% set user_info = frappe.utils.get_user_info_for_avatar(user_id) %}
<span class="avatar avatar-small" title="{{ user_info.name }}" style="{{ css_style or '' }}">
	{% if user_info.image  %}
	<img
		class="avatar-frame standard-image"
		src="{{ user_info.image }}"
		title="{{ user_info.name }}">
	</span>
	{% else %}
	<span
		class="avatar-frame standard-image"
		title="{{ user_info.name }}">
		{{ frappe.utils.get_abbr(user_info.name) }}
	</span>
	{% endif %}
</span>
{% endmacro %}
Use get_abbr method for abbr
fix: Use get_abbr method for abbr
