TYPO3 TCA l10n_mode exclude and MM relations - typo3

Question

in TYPO3 v10.4.9 when I use the following tx_csdummy_domain_model_product.php TCA
'items' => [
'l10n_mode' => 'exclude',
'config' => [
'type' => 'select',
'renderType' => 'selectMultipleSideBySide',
'foreign_table' => 'tx_csdummy_domain_model_item',
'foreign_table_where' => ' AND (tx_csdummy_domain_model_item.sys_language_uid IN (0,-1)) ORDER BY title ASC',
'MM' => 'tx_csdummy_product_item_mm',
]
],
],
and in the tx_csdummy_domain_model_item.php TCA
'products' => [
'l10n_mode' => 'exclude',
'config' => [
'type' => 'select',
'renderType' => 'selectMultipleSideBySide',
'foreign_table' => 'tx_csdummy_domain_model_product',
'foreign_table_where' => ' AND (tx_csdummy_domain_model_product.sys_language_uid IN (0,-1)) ORDER BY title ASC',
'MM' => 'tx_csdummy_product_item_mm',
'MM_opposite_field' => 'items',
]
],
],
it works in the default language as it should. But when I have both sites translated, something goes wrong.
For example I have porduct default (uid=1), product translated (uid=2), item default (uid=5) and item translated (uid=6).
A) If I save the product, then the uid of the translated product points to the default language uid of the item.
tx_csdummy_product_item_mm
uid_local uid_foreign
1 5
2 5
B) If I save the item, then the uid of the translated item points to the default language uid of the product.
tx_csdummy_product_item_mm
uid_local uid_foreign
1 5
1 6
With A I can't see the related product in the english version of the item in frontend.
With B I can't see the related item in the english version of the product.