There are two different types of transperineal biopsy, and you didn't say which one you had.
LATP (Local Anesthetic Transperineal) is now the most common type of biopsy, performed as an outpatient.
They usually take 12 cores, that being the limit of what they think patients can stand while conscious, but if they thought you were holding up well, they always prefer to take more, particularly if you have a large prostate.
Transperineal Template Biopspy, which is done as a day case in an operating theatre, under general anesthetic or epidural. For this type, because you are much better anesthetised, they normally take many more samples - figures of 30-50 not uncommon.
Before we had mpMRI scans which allowed guiding biopsies to areas of concern, there was a variation on this called a Mapping biopsy, where they would closely sample the whole prostate, and that could be 100 or more samples.
I would not read anything sinister into the number of samples taken - it's more about what the patient will tolerate, versus more samples making the procedure more reliable.