mac book air m2 ram throttling

I have a MBA M2 with 8GB of Ram, purchased Nov 2022. I'm a basic user of Office, Teams, Chrome browser, email, whatsapp desktop etc. All was fine until the most recent Ventura security update about 2 weeks back. Went to the Genius Bar who advised fresh re-install. Did not really help. They checked Hardware all fine.

Problem is that intermittently, RAM usage jumps to red level and I need to force quit something. For some reason it puts the entire Mail mailbox (40 GB) into RAM. I am using the Apple Mail app.

Driving me crazy, any advice kindly received.