vendor/szymach/c-pchart/src/Draw.php(2302): Deprecated - preg_split(): Passing null to parameter #2 ($subject) of type string is deprecated - Matomo 4.14.3-b1 - Please report this message in the Matomo forums: https://forum.matomo.org (please do a search first as it might have been reported already) [internal function]: Piwik\ErrorHandler::errorHandler(),#1/vendor/szymach/c-pchart/src/Draw.php(2302),#2/plugins/ImageGraph/StaticGraph/GridGraph.php(312),#3/plugins/ImageGraph/StaticGraph/Evolution.php(24),#4/plugins/ImageGraph/API.php(506),[internal function]: Piwik\Plugins\ImageGraph\API->get(),#6/core/API/Proxy.php(244),#7/core/Context.php(28),#8/core/API/Proxy.php(335),#9/core/API/Request.php(267)

After upgrading to PHP 8.1 above warning is showing up in the logs. This is all the information we have.