No. Ads are not currently a part of the Lark product.
As described in Lark's Privacy Policy, Lark may use de-identified data to advertise to potential new users and to improve the overall product experience. This is a standard practice that does not involve using your personal health data to show you ads within the app.
For full details, read Lark's Privacy Policy.
Still need help? Contact our support team via the webform at support.lark.com/hc/en-us/requests/new