The chacha20 family of ciphers are not considered insecure, and are an order of magnitude more efficient on servers that do not provide hardware acceleration for AES encryption (like all the raspberry pi models). Wireguard uses this cipher, it has been thoroughly analyzed and considered to be secure, so I see no reason why ChaCha20 should not be added to this list:
The chacha20 family of ciphers are not considered insecure, and are an order of magnitude more efficient on servers that do not provide hardware acceleration for AES encryption (like all the raspberry pi models). Wireguard uses this cipher, it has been thoroughly analyzed and considered to be secure, so I see no reason why ChaCha20 should not be added to this list:
https://github.com/haiwen/seafile-client/blob/73634229e4d2357ac2e7d1e5170b49b7c4bcde85/src/network-mgr.cpp#L29-L51
Link to this topic in the forums: https://forum.seafile.com/t/use-chacha-encryption-algorithms-instead-of-aes-for-https/14201/5