I removed my VS Redist (2k17) install, and reinstalled it.
Restarted the dedicated server - and relaunched with latest FiveM server (and Botan.dll)
No longer have the initial issue - however I still do see the stack trace mentioned at init. (Image above)
Note: If this is a non-critical known issue - just let me know and I’ll sleep soundly.
Edit: After some searching on the FiveM Discord it appears the CitizenFX team are aware - so disregard.
Edit 2: Incase anyone comes across this topic in a search and are having similar issues with Botan.dll errors on launch - keep in mind, if you happen to be running multiple instances of FiveM server & botan.dll at the same time - running an older version alongside the newer will throw the error upon restarting the newer instance.
Save yourself the stress and update both servers fivem data - or you’ll have to shut down the legacy server in order to launch the newer one again.