Currently the banner is affecting the total LCP when a crawler, for instance googlebot is accessing and crawling the site.
It would be amazing if you built crawler authentication into cookie-script, to avoid LCP issues and ensure the best possible performance. Making sure that the banner is never displayed to bots, will greatly benefit the LCP score.
Here's the documentation required to authenticate bots from google: https://developers.google.com/search/docs/crawling-indexing/verifying-googlebot