Thanks for getting in touch - this is definitely an odd error. I was able to do a little testing on my end and encountered a similar error when I replicated your syntax in my test environment. I did find that the query seemed to work when I removed the extra " ' "/backticks from the query. For example I changed something like this:
I also removed the space between the tag text you want to limit from the search and the "tag_not" param field. If you haven't yet tried this, can you give this a go and let me know if the query was successful?
If not - if you can provide an X-Request ID from the response you'll receive from that query, can you share that with me? Having that ID will allow me to take a look at the logs on our end so we can further troubleshoot this.
Hope this helps - feel free to reach out here with that Request ID if we can further assist with this.