/**
 * @Condition(
 *   id = "node_type",
 *   label = @Translation("Node Bundle"),
 *   context = {
 *     "node" = @ContextDefinition("entity:node", label = @Translation("Node"))
 *   }
 * )
 */

/**
   * Return current term.
   */
  public function getCurrentTerm() {
    $term = null;

    // Below we are using the general method to obtain the objects.
    // DrupaltaxonomyEntityTerm::load($tid) is the other

    // Get the unaliased path in the form /taxonomy/term/tid.
    $current_path = Drupal::service('path.current')->getPath();

    preg_match('//taxonomy/term/d+/', $current_path, $matches);

    // Return null if not in proper form.
    if (count($matches)) {
      // Find the parameters for this route.
      $params = DrupalCoreUrl::fromUri("internal:" . $current_path)
        ->getRouteParameters();

      // Fetch the taxonomy object.
      $entity_type = key($params);
      $term = Drupal::entityTypeManager()
        ->getStorage($entity_type)
        ->load($params[$entity_type]);
    }

    return $term;
  }
}

MYMODULE.taxonomy_term_context:
    class: DrupalMYMODULEContextProviderTaxonomyTermContext
    arguments: ['@current_route_match']
    tags:
      - { name: 'context_provider' }

<?php

namespace DrupalMYMODULEContextProvider;

use DrupalCoreCacheCacheableMetadata;
use DrupalCorePluginContextContext;
use DrupalCorePluginContextContextDefinition;
use DrupalCorePluginContextContextProviderInterface;
use DrupalCoreRoutingRouteMatchInterface;
use DrupalCoreStringTranslationStringTranslationTrait;

/**
 * Sets the current taxonomy term as a context on taxonomy term routes.
 */
class TaxonomyTermContext implements ContextProviderInterface {

  use StringTranslationTrait;

  /**
   * The route match object.
   *
   * @var DrupalCoreRoutingRouteMatchInterface
   */
  protected $routeMatch;

  /**
   * Constructs a new object.
   *
   * @param DrupalCoreRoutingRouteMatchInterface $route_match
   *   The route match object.
   */
  public function __construct(RouteMatchInterface $route_match) {
    $this->routeMatch = $route_match;
  }

  /**
   * {@inheritdoc}
   */
  public function getRuntimeContexts(array $unqualified_context_ids) {
    $result = [];
    $context_definition = new ContextDefinition('entity:taxonomy_term', $this->t('Taxonomy term from URL'));
    $value = NULL;
    if (
      ($route_object = $this->routeMatch->getRouteObject())
      && ($route_contexts = $route_object->getOption('parameters'))
      && isset($route_contexts['taxonomy_term'])
    ) {
      if ($term = $this->routeMatch->getParameter('taxonomy_term')) {
        $value = $term;
      }
    }

    $cacheability = new CacheableMetadata();
    $cacheability->setCacheContexts(['route']);

    $context = new Context($context_definition, $value);
    $context->addCacheableDependency($cacheability);
    $result['taxonomy_term'] = $context;

    return $result;
  }

  /**
   * {@inheritdoc}
   */
  public function getAvailableContexts() {
    $context = new Context(new ContextDefinition('entity:taxonomy_term', $this->t('Taxonomy term from URL')));
    return ['taxonomy_term' => $context];
  }

}