See below warning we got after trying to upgrade Cloud to PHP 8.1:

/var/www/html/plugins/ImageGraph/StaticGraph/GridGraph.php(143): Deprecated - Implicit conversion from float-string "39.15" to int loses precision - Matomo 4.13.3 - Please report this message in the Matomo forums: https://forum.matomo.org (please do a search first as it might have been reported already) #0/plugins/ImageGraph/StaticGraph/GridGraph.php(143),#1/plugins/ImageGraph/StaticGraph/Evolution.php(24),#2/plugins/ImageGraph/API.php(506),[internal function]: Piwik\Plugins\ImageGraph\API->get(),#4/core/API/Proxy.php(244),#5/core/Context.php(28),#6/core/API/Proxy.php(335),#7/core/API/Request.php(267),#8/core/ReportRenderer.php(277),#9/core/ReportRenderer/Html.php(175)

I don't think I have more information unfortunately.