-----BEGIN BITCOIN SIGNED MESSAGE-----
busminer at 23.05.2020 Proof that I own 3NnxF61TMcc6gXLM6Gqk6qNPL7VnF2daXq
-----BEGIN SIGNATURE-----
142eRsdiiteSL6pbBAV2NXRRZuCwz94pYP
JFKj8di8Jx3TZsXNcY4mOOWCo4evOUA6ZISt86j4zEw6NXS/x3gp9qR0zq8v3G9T42/4QPUgFiWz76XIm+HbwQk=
-----END BITCOIN SIGNED MESSAGE-----
This is what you meant:
-----BEGIN BITCOIN SIGNED MESSAGE-----
busminer at 23.05.2020 Proof that I own 3NnxF61TMcc6gXLM6Gqk6qNPL7VnF2daXq
-----BEGIN SIGNATURE-----
3NnxF61TMcc6gXLM6Gqk6qNPL7VnF2daXqJFKj8di8Jx3TZsXNcY4mOOWCo4evOUA6ZISt86j4zEw6NXS/x3gp9qR0zq8v3G9T42/4QPUgFiWz76XIm+HbwQk=
-----END BITCOIN SIGNED MESSAGE-----
You failed to change your address in the signature to your own. Which after doing so, does
verify.
EDIT: Copy Paste oversight, I'm sure.