1. Have PHP 7.3.5. For some reason it is more strict than 7.2.18.
2. Have a default graph like CPU Load.
3. Have error displaying to some file. You will see it in view.
4. Open graph and observe the error in that file.

time() expects exactly 0 parameters, 1 given [chart2.php:168 -> CLineGraphDraw->draw() -> CLineGraphDraw->selectData() -> time() -> CConfigFile->{closure}() in include\classes\graphdraw\CLineGraphDraw.php:180]

That is not the only place. Several more places have time(null) in code. The function is not supposed to accept any parameters.