My god.
Even on LinkedIn it is optional.
I was out of work for a year and a half for personal reasons, and I conceal that fact from clueless tech recruiters by having my previous place "2013-2016" and my next as "2017-now". As soon as service "forces people" to fill their form as "tech recruiters" designed, they can just go south.
"Can you explain the gap in your work history from May 1997 to March 1998?"
My answer:
"You're asking about a gap more than 20 years ago? I just didn't work for a bit, that's all."
Some recruiters look for red flags in order to dismiss a CV. Year out of work could be such a flag. My job is to hide that red flag. Once being interviewed, I will provide the details if asked.
I almost always see the dates with a month.
CVs are primarily consumed by people who hire people, why wouldn't you listen to what they say?
If you had to be out of work for a year and a half for personal reasons, just put it there. Trying to conceal stuff can work, but might not; hence, isn't the most conservative idea. All the best.