To allow Looker to be embedded in external web pages such as monday.com, the website's domain needs to be whitelisted in your Looker admin settings.
Embedded Domain Allowlist
The Looker Admin menu contains an Embed page within the Platform section where administrators configure embedded content settings.

Add the following domains to the embedded domain allowlist:
https://monday.dsapps.info
https://everyday.dsapps.info
For a full list of domains used by David Simpson Apps, visit https://dsapps.dev/policies/domains/.
Same-Origin Protections for Looker Login Pages
If users haven't logged in previously, the Looker authentication screen will display within monday.com. Using same-origin protections for your Looker login pages may prevent the login screen from appearing for private embeds.
To resolve login screen visibility issues, enable the Same-Origin Protections for Looker Login Pages setting in the Looker admin panel.