This is terrible advice, even if I assume you are also using a key-file on a removable usb. An attacker can brute force decrypt your db. There is no rate limiting when you literally have the database file, they could replicate it across thousands of servers each with dozens of cores, each core trying a dozen keyphrases per second. That's assuming a motivated attacker like a government or crypto scammers, but why open yourself to that possibility?

Yes and no. You can store them in a free cloud account, provided you have local copies; there's a risk your access to the cloud storage could be denied. A security risk is that they could harvest these databases, and decrypt them later.

I think your best bet, if you were to use free services, is to delete old databases from the cloud. Encrypt the new databases with the updated password manager and a new master password.

Why would you do that? Just sync thr database with Syncthing and keep it locally on your devices. I'd never put my pw dB in a publicly available cloud online, even though it's encrypted.