database – Unable to delete a tempstore that contains an en– or em dash —

$keyword = '2020–2021';
$tempstore = Drupal::service('tempstore.shared')->get('my_module_name');

this throws an error:

DrupalCoreDatabaseDatabaseExceptionWrapper: SQLSTATE(HY000): General error: 1267 Illegal mix of collations (ascii_general_ci,IMPLICIT) and (utf8mb4_general_ci,COERCIBLE) for operation '=': DELETE FROM {key_value_expire} WHERE ("name" IN (:db_condition_placeholder_0)) AND ("collection" = :db_condition_placeholder_1); Array ( (:db_condition_placeholder_0) => 2020—2021 (:db_condition_placeholder_1) => tempstore.shared.my_module_name ) in DrupalCoreKeyValueStoreStorageBase->delete() (line 52 of core/lib/Drupal/Core/KeyValueStore/StorageBase.php).

As far as I can tell it’s not an issue with the database but rather having the the en or em dashes present in the keyword. I’ve tried escaping with Html::escape() and utf8_encode() but they didn’t seem to help.