ZBXNEXT-5228 involved changes in export XML schema. In Zabbix 4.2, host TLS connection was defined like:

<tls_connect>4</tls_connect>
<tls_accept>5</tls_accept> 

Starting with 4.4, TLS is defined as:

<tls_accept>
  <option>NO_ENCRYPTION</option>
  <option>TLS_CERTIFICATE</option>
</tls_accept> 

Changes made to implement this change was done wrongly (see ZBX-17165 for more details). Starting from 5.0, this should be fixed by adopting API for new data structure. CTransformImportConverter involved in ZBX-17165 should be removed from Zabbix 5.0.