There is a gentlemen's agreement not to do it, but realistically I'm indifferent either way to it. If anything, I think what we've seen in recent months is that posting lap times often makes newcomers
more comfortable, not less, since in a lot of cases it's the newcomers asking for them. Making their discussion verboten doesn't help in that case, since they both get told off for asking, and don't even get an answer to their question.
Either way, anyone reading this post is welcome to know that it's fine for you to join no matter what lap time you do, and lap times by themselves don't matter, all that matters is having fun
If doing better lap times makes it more fun for you, more power to you, but it's not an entry requirement.
For the timebeing, I'm interpreting that gentleman's agreement as "until the race is over, don't discuss front-of-pack times, but discussing midfield times is fine". I can see how alien times might put someone off.