This is not an issue specific to Rails.
The way the CSP implementation works is that the server sends a response header with the CSP rules
For example, these are greensock's CSP rules
Sometimes people choose to relax the CSP rules by using unsafe-inline which is not recommended since it defeats the purpose of having a CSP.
Or alternatively, we can set unsafe-hashes rule and pass the computed sha256 value of the code we want to run, this should be avoided when possible since an attacker can still take advantage of this if they're able to create a method with the same signature.
In this case, we can add to our rules style-src 'sha256-KNzsEJVbLeUYL5BJED4PPrsiMvQsDZ6wNHiw+M2zQ+M=' as a temporary solution but in future, we might consider using an alternative library since we want to keep our CSP as strict as possible.
This stack overflow answer explains why the code mentioned above breaks the inline-style rule https://stackoverflow.com/a/42402277/5781329
Thank for your help