PHP 7.3 was released nearly three years ago and reached its End-Of-Life (EOL) this December.
This means that support for this version officially ended on December 6 2021 and no further updates (security or feature-wise) will be provided by the PHP team.
If your website is using PHP 7.3, or a lower version, you should upgrade to a newer version as soon as possible to gain the benefits offered by newer versions (both from a features and security perspective).
PHP 7.4 is the version currently recommended by WordPress and is supported by the majority of the popular plugins. PHP 8 is however supported by WordPress (as well as some plugins) and is gaining in popularity as developers make the switch to this latest version.
If you’ve yet to upgrade to a newer version of PHP, this is easy to do from your Dashboard. Follow this guide for full details on how to make the switch. Before upgrading your live website (production environment), you can use the staging feature to test your website compatibility. Using a staging site is a great way to spot any potential plugin issues and allows you to make any necessary changes with no downtime.
As always, should you need any help with this upgrade please submit a support ticket from within your Dashboard and one of the team will get back to you.