It could be a lowballing attempt, it could be a buyer's valuation that is made genuinely and just deemed wide of the mark by the seller. Either way it doesn't always end up with the selling club caving in as the big club's shadow looms above it. I think this is going to be one of those occasions.
My assumption is going off the repeated statements by the Monaco owner, plus I don't think he's talked in the same terms about any of Mendy, Bernardo, Mbappe or Bakayoko. I'd be very surprised if either Arsenal's offer substantially increased, or if Monaco accepted it
What is your issue here exactly anyway? Classic forum stuff, two unproveable opinions, neither of us can know and that's the only sure thing about it.