Can this issue be related to the Certification Authority that provides the certificate?
No, the Certificate Authority has nothing to do with the ciphers supported by the server. The server supports a cert of ciphers according to its capabilities and configuration.
Or this issue is related to the possibility of older browser usage?
Older browsers don't support newer ciphers. The question is, do you want to jeopardize the security of all your users just to support people who still run Internet Explorer 8, which has been End-of-Life since Mid-2018.
What to do now?
- Remove Support for SSLv3, TLS 1.0 and TLS 1.1.
- Configure TLS 1.2 to only support strong ciphers, which provide Forward Secrecy
SOGIS recommends only using the following ciphersuites (see Chapter 6.1):