To prevent irrelevant keys from being offered, you have to explicitly specify this in every host entry in the ~/.ssh/config (on the client machine) file by adding IdentitiesOnly like so:
Host www.somehost.com
IdentityFile ~/.ssh/key_for_somehost_rsa
T. Venters, M. Reno, and J. Krizmanic. (2022)cite arxiv:2206.02730Comment: 10 pages, 7 figures, 2 tables, Proceedings of the 37th International Cosmic Ray Conference (ICRC 2021).