Hi,

When you have both lots with expiration dates and lots without expiration dates in the same category in inventory management and you have not specifically established a removal method, the default removal method is often First-In, First-Out (FIFO).

When you sell or use things from that category, the oldest items in your inventory will be the first to be deleted. It means that things with earlier expiration dates will be used or sold first in the context of items with expiration dates. This strategy is commonly used in inventory management to ensure that older things do not become obsolete or expire before newer items.

Please refer the below link for more information

https://www.cybrosys.com/blog/what-are-the-different-types-of-removal-strategies-in-odoo-16

Hope it helps