> We recommend enabling RSA/SHA1 only as a stopgap measure until legacy
implementations can be upgraded or reconfigured with another key type
(such as ECDSA or Ed25519).
openssh.org/txt/release-8.8 https://www.openssh.org/txt/release-8.8
2021年の時点でrsaはやめておけってOpenSSHのリリースノートに書いてありますからね
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