I recently was in an awkward situation when ordering my new passport. Most times I got to sign some papers I have some signature which is a few waves, not forming many letters. In the passport office the clerk told me they can't recognize any enough letters in there, so I had to do multiple attempts till they were happy ... now my passport got a signature I won't be able to replicate ever.

(I do some handwriting for notes taking, but that's some writing based on block letters, not script as in a signature)

This is a very strange requirement, to be honest. E.g. what about foreigners whose native script is not the same, so their (pre-existing) signature is unparseable to that clerk anyway?

FWIW I have a signature that is barely recognizable as my two initials, and I have never had it rejected on such grounds in the five different countries (using two different scripts) I've had to sign documents using it.

>now my passport got a signature I won't be able to replicate ever

I'm not sure I could ever prove I am who I say I am using my signature. My wife signs my name most of the time when it's necessary for a check or a health form for the kids or whatever. Whenever I go to vote, I try to sneak a look at their copy of the form to see how I signed it when I registered. I think my credit union has one 'on file' for me, but I'm sure it's nothing like how I actually sign my name and is from ~25 years ago.