WordPress on IIS crashes intermittently

My wordpress site running on IIS has been crashing every once in a while with “There has been a critical error on your website”
If I restart IIS or the AppPool, it starts working again.
It’s a pretty basic wordpress site, just a few basic plugins

When I look at the php error log I find this:

(11-Jun-2021 05:05:56 UTC) PHP Warning:  require_once(C:inetpubwwwrootwp-includess): failed to open stream: No such file or directory in C:inetpubwwwrootwp-includessodium_compatautoload.php on line 40
(11-Jun-2021 05:05:56 UTC) PHP Fatal error:  require_once(): Failed opening required 'C:inetpubwwwrootwp-includessodium_compat/src/SodiumException.php' (include_path='.;C:phppear') in C:inetpubwwwrootwp-includessodium_compatautoload.php on line 40

It says it fails opening the file, but the file does exist, and I can open it. I thought the different slashes in the filename might be the problem, but I can copy and past that exact path into the Run prompt and it opens fine.

At the time of the problem, available memory seems fine, and not noticing any traffic spikes.

Windows Server 2019 datacenter
IIS 10.0
MySql 5.7.31
Wordpress 5.5.5
Php 7.3.13

What troubleshooting steps would you recommed?