That's where Vaultwarden (https://github.com/dani-garcia/vaultwarden) comes in. You can use the official Bitwarden clients and fully host the backend by yourself. You don't need to trust Bitwarden with your data and can probably upgrade only when you need to, as the clients surely have some sort of backward compatibility.
Can you even imagine what kind of stuff they had to tell their investors in order to get 100m?