The Sphider 3.4.3-MB and SphiderLite 1.1.3 releases fix a number of issues which arose under PHP 7.3 and PHP 7.4. It was found that as of PHP 7.3, image indexing in Sphider MB releases had broken. This has been resolved. A couple of cleanup items were also done with each.
Sphider 2.4.3-PDO is a one time maintenance release to keep the PDO version running under PHP 7.3 and PHP 7.4. It is not intended to resume development on the PDO version at this time.