Forms > add taxonomy field > adds selected taxonomy to list

Dear,

I have several forms. They all have taxonomy field with type select or multiselect. When an enduser is selecting one of the displayed taxonomy and save his post, the form is adding the ID of the selected taxonomy to the taxonomy. This is a big issue, because the taxonomy is getting new items name (the id of the selected taxonomy) each time someone is submitting a new post, in place of only registering the selected taxonomy.
The purpose of the taxonomy field is to let end-user select existing taxonomies to link to their new post and not to add the ID of the selected taxonomy to the taxonomy list.
How to solve this issue?

https://wordpress.org/plugins/wp-user-frontend/