The key depends on what you do and who you give it to, that is, leave a phone number and name for colleagues and couriers, which is generally no problem.

Anyway, you need to confirm what this note is for.

If you just write it on the table and don't know who took it, there is a hidden danger and it may be used to forge a signature or something.

But don't worry too much. Now important contracts, signatures and the like generally require me to bring my ID card to handle them. It's no use just having a signature and a phone number.

As long as you don't write down your address, your relatives' phone numbers and so on, at most, there are small advertisements and scammers calling you.