I think that really depends on feature usage. You can use Argo/Cloudflare tunnels to route to private backends that are normally unroutable. In such a setup, it might be quite difficult to remove Cloudflare since then you have no edge network and no ability to reach your servers without another proxy/tunnel product.

If you're using other features like page rules you may need to stand up additional infrastructure to handle things like URI rewrites.

If you're using CDN, your backend might not be powerful enough to serve static assets without Cloudflare.

If your using all of the above, you're work to temporarily disable becomes fairly complicated.

It depends. The site is up, but now you're pumping 10x/100x the traffic. What are you scaling up?

Suddenly you're not blocking bots or malicious traffic. How many spam submissions or fake sales or other kinds of abuse are you dealing with? Is the rest of your organization ready to handle that?