I have been making a few tests recently in a new project, and even in my old portal i have never faced ban issues in free api.
But, why using a free service if you're planning to work on a project? Why having to be dependent from quick and rough solutions such as blockchain.com's API? By setting up a node it'll come cheaper than you may think. Then you could install a script like
mempool.space's and enjoy the development with no third parties needed to trust. (The open-source project “mempool” comes with its API, if I'm not mistaken)
For example, blockchair API have a limit of 1440 requests per day for free
Blockchair was free all that time? I thought you could only use if you paid. (which also comes with the premium features)