Advanced Custom Fields (ACF) - Adds a custom ACF location rule to field groups to choose "Specific Term" on taxonomy pages. This location rule is available to any field group, allowing you to show fields for a specific term within a taxonomy.

rs-acf-specific-term-location.php

<?php
/*
Plugin Name: RS ACF Specific Term Location
Description: Adds a custom ACF location rule "Specific Term". It lets you restrict a field group to show only for a specific term when editing a term in the backend.
Version: 1.0.2
*/

// category ancestor location rule
function rs_acf_location_types_specific_term( $choices ) {
	if ( !isset( $choices['Forms']['specific_term_id'] ) ) {
		$choices['Forms']['specific_term_id'] = 'Specific Term';
	}
	
	return $choices;
}

function rs_acf_location_rule_values_specific_term( $choices ) {
	$choices = acf_get_taxonomy_terms(); // from "Post Taxonomy" location
	return $choices;
}

function rs_acf_location_rule_match_specific_term( $result, $rule, $screen ) {
	// Most of this is from acf_location_post_taxonomy::rule_match
	$s = function_exists('get_current_screen') ? get_current_screen() : false;
	if ( !$s || !($s instanceof WP_Screen) ) return false;
	if ( $s->base != 'term' ) return false;
	
	$taxonomy = acf_maybe_get( $screen, 'taxonomy' );
	$current_term_id = acf_maybe_get( $_GET, 'tag_ID' );
	
	// bail if no term
	if( !$current_term_id ) return false;
	
	$current_term = get_term_by( 'term_id', (int) $current_term_id, $taxonomy );
	
	// bail if term not valid
	if( !$current_term || is_wp_error($current_term) ) return false;
	
	// get term data
	$data = acf_decode_taxonomy_term( $rule['value'] );
	$term = get_term_by( 'slug', $data['term'], $data['taxonomy'] );
	
	// attempt get term via ID (ACF4 uses ID)
	if( !$term && is_numeric($data['term']) ) {
		$term = get_term_by( 'id', $data['term'], $data['taxonomy'] );
	}
	
	// bail early if no term
	if( !$term ) return false;
	
	// match
	$result = $term->term_id === $current_term->term_id;
	
	// reverse if 'not equal to'
	if( $rule['operator'] === '!=' ) {
		$result = !$result;
	}
	
	// return
	return $result;
}

add_filter( 'acf/location/rule_types', 'rs_acf_location_types_specific_term' );
add_filter( 'acf/location/rule_values/specific_term_id', 'rs_acf_location_rule_values_specific_term' );
add_filter( 'acf/location/rule_match/specific_term_id', 'rs_acf_location_rule_match_specific_term', 10, 3 );

This is a WordPress plugin in a single PHP file. You can zip it and upload it like a normal plugin.