TL;DR: If your SSH key is of the ECDSA type with a key length of 521 bits, make a new one and take care to remove the public key belonging to the burned one from all authorized_keys files. Luckily, ecdsa-sha2-nistp521 is (AFAIK) not the default if you used ssh-keygen or PuttyGen with the default settings. https://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-p521-bias.html