investigating TinyMCE inserting line breaks into some list items

<li><span style="line-height: 115%;">Know how to find guidance for referencing your work correctly in UWE Harvard</span>.</li>

<li><span style="line-height: 115%;">Know how to find guidance for referencing your work correctly in UWE Harvard.</span></li>

<ul class="emphasis-list check">
 <li>Pass rate: <strong><span class="text-success">99%</span></strong></li>
 <li>Average mark: <span class="text-success"><strong>83%</strong></span></li>
 <li><strong><span class="text-success">85%</span></strong> of the students' marks were above <strong><span class="text-success">70%+</span></strong></li>
</ul>

$_post[$name] = $_post["{$name}_editor_contents"];

$_post[$name] = str_replace(array("\r", "\n"), '', $_post["{$name}_editor_contents"])

function jrCore_remove_unwanted_breaks($string)
{
    // fix ul
    if (strpos(' ' . $string, '')) {
		if (strpos(' ' . $string, ' $line) {
                	if (strpos(' ' . $line, '>')) {
                    	$_tmp[$k] = str_replace('>', '>', $line);
                    }
                }
                $string = implode("\n", $_tmp);
            }
		}

function jrCore_remove_unwanted_breaks($string)
{

    if (strpos(' ' . $string, "<br>")) {
        
        // fix ul
        if (strpos(' ' . $string, "<ul")) {
            $_tmp = explode( "\n", $string);
            if ($_tmp && is_array($_tmp)) {
                foreach ($_tmp as $k => $line) {
                	if (strpos(' ' . $line, "><br>")) {
                    	$_tmp[$k] = str_replace("><br>", '>', $line);
                    }
                }
                $string = implode("\n", $_tmp);
            }
        }

<h1>some big text</h1>
<p>then some small text</p>

<h1>some big text</h1><br>
<p>then some small text</p>

<h1>some big text</h1><p>then some small text</p>

<h1>some big text</h1>
<p>then some small text</p>

remove_linebreaks : true