Are Notion Widgets Safe?
Mostly yes, and the reason is structural rather than something you have to take on trust. A widget runs inside a frame, so it cannot read your Notion pages, cannot see your databases, and cannot tell what else is on the page around it. Browsers enforce that. You never grant a widget access to your workspace because there is nothing to grant.
What it genuinely cannot do
Read your data, write to it, or see the rest of the page. This is a different situation from an integration, where you do grant access and can therefore revoke it later.
What it can see
That it was loaded. Any embed knows it was opened, roughly when and roughly from where. That is how a visitor counter works at all. If a page is properly sensitive, worth knowing before you put any third party embed on it.
What you upload
Images in a carousel live on the provider's servers. If the page is private, ask whether the image address is guessable. Ours are not indexed and not listed, but the honest framing is to treat anything inside a widget as semi public, because it is served from outside your workspace.
If a tool disappearing worries you more than a tool watching, that has its own page: what happens if a widget tool shuts down.
Safety in shared templates
If you duplicate somebody else's template you inherit their embeds. Those widgets belong to whoever built them, run on their account, and can be changed by them at any time without telling you.
Usually harmless, occasionally not. Before building something important on a downloaded template, look at what is embedded in it and decide whether you would rather rebuild those widgets on your own account. It takes a few minutes and puts the pieces under your control.