Recently, Uptime Robot has made a few changes to its API by limiting the API calls per minute.
If you want to increase the API calls per minute, kindly upgrade your plan with them here.
Also, check the link below for more information.
When you go to the Monitor > Uptime Monitor page, please wait a few minutes and do nothing.
Then try creating a new monitor by selecting less than ten sites or loading the uptime robot data.
