The first parameter of the filter gets its value from function wc_get_product_term_ids:
http://hookr.io/filters/woocommerce_get_related_product_tag_terms/
This function returns an array of term_id
s instead of objects:
https://docs.woocommerce.com/wc-apidocs/source-function-wc_get_product_term_ids.html#860-871
So you can match the term id values directly or you can use get_term_by to get one of the term objects in the comparison.
e.g. getting the term on the right hand side of the comparison:
$termnames = array(
'Đồng Hồ Thụy Sỹ',
'Đồng Hồ 6 Kim',
'Citizen Eco-Drive',
'Seiko Kinetic',
'Seiko Solar',
'Đồng Hồ Dây Da Nam Nữ'
);
foreach($terms as $key => $term) {
$t = get_term_by('id', $term, 'product_tag');
if(in_array($t->name, $termnames, true) || 'dong-ho-thuy-sy' === $t->slug) {
unset($terms[$key]);
}
}