When I first joined a US startup, they said "you can take unlimited PTO -- we suggest starting with a week per year"... I negotiated that up to the five weeks that are standard here in Denmark.
Needless to say, I didn't accept the job in the end.
If they don’t know, that’s a red flag. Id expect it to be about 20-25 if it also includes sick leave. 30-40 means people really take the policy seriously.