Thanks,
I don't think it would be out of date software in this case (Joomla is up to date, my extensions too, and I'm running PHP 7.3). I did see some past threads in here that sounded somewhat similar (though not exactly the same) that seemed to be resolved with updates to the Gantry Framework, but in my case I'm up to date on that front already.
I did reach out to the service provider providing the control panel interface about the issue first and after the last time it occurred they provided the following response:
The root cause of this issue is the PHP-fpm process.
There are three most likely causes:
A bug in the app's PHP code, such as a buggy WordPress plugin
A bug in a PHP extension you've added to your server
Your server running out of memory
The most common cause of these errors is buggy PHP code in your app.
The best solution is to disable all WordPress plugins, custom themes, and other custom code until you identify which code is causing the problem.
Even if you haven't identified the cause of the problem, you may be able to get your app working again by restarting PHP.
I wish the issue was easier to reproduce so it could be troubleshooted more effectively, but unfortunately it just seems to happen sporadically, and I don't know exactly what code on the PHP end could cause an issue with the PHP-fpm process.
Regarding the server side of things, the server has 32 GB of RAM (and it's a more dedicated instance and only 3 GB of RAM is currently being used) and it only has the standard PHP extensions that you would expect to be enabled and it's only running this one site.
No worries about not being able to provide any suggestions at this point, if I find a true fix I'll try and update here so the topic might be helpful to someone else experiencing the same issue.