Indeed, I upgraded from 7.1.7 to 7.2.2 and the analytics graphical chart is not displayed any more. I am using Yandex-Browser for GNU/Linux Metztli Reiser4 (Debian Buster on steroids ;-) / Engine X 1.19.1, PHP 7.4.5, MariaDB 10.5.8 (LEMP).

I can confirm same bug with 7.3.0-beta released on 2020-10-23 and Debian Bullseye.
DB: 5.5.5-10.3.24-MariaDB-2
PHP: 7.4.11

For those b2evo users experiencing subject issue, please see dirty hack:

"Canvas charts not displaying in b2evolution 7.2.2 / 7.2.3 workaround"
< https://forums.b2evolution.net/canvas-charts-not-displaying-in-b2evolution-7-2 >

Best Professional Regards.