WordPress TinyMCE editor delete BR tags

I’m sorry, I speak a little English.

Installed:

Classic Editor 1.6.2 plugin (WordPress 5.8.1)

If I click from “Text” to “Visual” tab, then back to “Text”, removed the <br/> tags. I need these <br/> tags.

Screenshots:

1. Text: https://i.imgur.com/VYizddC.png

2. Visual: https://i.imgur.com/lgROXGQ.png

3. Text: https://i.imgur.com/CtSHndf.png

(removed the <br/> tags)

The plugin settings wp-admin page:

View post on imgur.com

I try, but does not work:

~/wp-content/themes/mytheme/functions.php

remove_filter( 'the_content', 'wpautop' );

function uncoverwp_tiny_mce_fix( $init ) {

    $init [ 'remove_linebreaks' ] = false;
    $init [ 'convert_newlines_to_brs' ] = true;
    $init [ 'remove_redundant_brs' ] = false;

    return $init;

}

add_filter( 'tiny_mce_before_init', 'uncoverwp_tiny_mce_fix' );

What is the solution?

Thanks.