WordPress does not save certain html?

Issue: If I edit and update a post in the “text” area and go to the “visual” editor and then come back to the “text” editing area, in some instances the code is changed or deleted. A change example might be removing <br> and replacing it with  (I know that   is used instead in WP).

Is this a self editing feature in WP? No other text editors delete or alter markup for you.

I’m using Woocommerce on top of WordPress but this happens on a non-Woocommerce WordPress site as well.