Name: GotoSocial
Homepage: https://gotosocial.org/
Short description: GoToSocial is an ActivityPub social network server, written in Golang.
Optional API documentation URL: https://docs.gotosocial.org/en/latest/api/swagger/
This link may also help: https://docs.gotosocial.org/en/latest/federation/federating_with_gotosocial/
It seems that Keyoxide did trying to parse the Gotosocial user's actor while performing verification, however the request was rejected by Gotosocial due to "response username mismatch":
timestamp="09/03/2024 23:04:12.866" func=server.glob..func1.Logger.func13.1 level=ERROR latency="180.76772ms" userAgent=doipjs/1.2.9 method=GET statusCode=500 path=/users/<username> clientIP=65.108.220.97 pubKeyID=https://keyoxide.org/users/keyoxide#main-key errors="Error #01: AuthenticateFederatedRequest: error dereferencing account https://keyoxide.org/users/keyoxide: enrichAccount: error webfingering remote account keyoxide.org@keyoxide.org: fingerRemoteAccount: response username does not match input for @keyoxide.org@keyoxide.org: %!w(<nil>)\n" requestID=htp7a9ce0400115e35h0 msg="Internal Server Error: wrote 54B"