To comply you must provide 'the Corresponding Source for the Program or the modified version, and the Corresponding Source for all programs that you use to make the Program or modified version available as a service'
A plain reading of this means that for a standard web app you would need to release not just the application code, but also code for the web server you are using, the os you are using, its drivers, device firmware, the os/firmware for your routers, your deployment stack, and probably more I'm missing. You better not trigger a deployment from a Windows computer using Chrome!
Even if I'm using open-source stuff for all of that it would need to have licenses compatible with SSPL such that I can relicense and release them all under the SSPL. I believe GPL is incompatible so that counts out most software I would use to host a webapp.
To me it seems like a fundamentally unreasonable license because for all practical purposes it is entirely impossible to comply with section 13.