Timezone function-WP 5.3

Hello, is there is an update available that is compatible with WP 5.3?
Specifically to address the Time Zone update found in this post

https://www.ads-software.com/support/topic/timezone-is-off-displaying-utc-on-all-events/#post-12138155

After disabling the JOAN plugin our event times were all correct. With that it seems JOAN might be using the now deprecated – date_default_timezone_set function?