Linux App Service (B1): system process memory rises to ~95% every night since Nov 10, not caused by the app

Since 10 November 2026 we see a daily block of extra CPU and memory usage on our Linux App Service plans that does not come from our application. We would like to know whether this is known platform activity, and how to avoid it.

Setup

• Region: West Europe
• Two Linux App Service plans, both Basic B1 with 1 instance, each running one Node.js web app (production and staging)
• Both plans have the identical set of outbound IP addresses, so we assume they share a scale unit. They run on different worker instances.

What we see

• Every night since 9/10 November there is a block of about 8 to 9 hours:
  • production plan: 02:00 to 11:00 UTC
  • staging plan: 23:00 to 07:00 UTC (3 hours earlier, starting the same night)
• During that block the plan CPU is about 38 to 42% (baseline 20 to 23%), and the plan memory peaks at 88 to 91% (hourly average). Our memory alert (above 85%) fires daily.
• In the 27 days before, neither plan showed this pattern.

Why we think it is not the application

• The app has almost no traffic in these hours, and its working set does not rise (it actually drops).
• In "Diagnose and solve problems" > "Linux Memory Drill Down" the "System Processes Memory Usage (ps)" graph shows the total system memory rising to 90 to 95% in exactly this window, while the "App Svc Platform processes" line stays flat or even drops (see attached graph). The user processes of the site stay flat.
• No deployments or configuration changes before or during the first occurrence.
• Resource Health shows "Available" for both plans and both sites. There are no Service Health events and no activity log entries for this period.

Questions

1. Is there known platform activity (maintenance, agents, updates) on Linux workers in West Europe since 10 November that could explain this?
2. Is there a way to see which system processes use this memory, or to avoid it?
3. Would scaling up (B1 to B2) or moving the plan to another scale unit be the recommended mitigation?

Thank you.