Circumcision in 1st temple period

So elsewhere in the internet/Reddit/it all started with a podcast, someone had the brilliant idea to discuss circumcision. I was bored and annoyed and replied.

It seems it’s an intactivist talking point that Jewish circumcision as practiced now is “new” because during the first temple period (so not so new, huh?) it was done on adults and not the entire foreskin was removed.

This sounds like utter BS to me. It’s also irrelevant because who gives a flying fork? How is that relevant to anything?

But in any case, is this true in any way? Where are they getting this from?

Again, I too think it’s a strange attempt at some gotcha. But just wondering if there is any reasonable basis to this

Thanks