I had a feeling that Real Madrid will find it difficult to win Las Palmas because the hosts haven't won their last eight home games and that coupled with the fact that Mallorca were able to hold them to a draw on opening match day, that sort of boosted their confidence and must say they had the better opportunity to get all three points because of the way they brought the game to Madrid.
Something I've noticed about the Los Blancos is that they aren't used to working under pressure. If you score first and start besting them at their game in the area of counter attacks and quick passes, you'd see them losing focus and becoming desperate thereby opening more opportunities for their opponents to take advantage of.
This is the second draw in three games and that's not like them and even though I said earlier that this season would be tough for them, I least expected they are going to start misbehaving from the beginning.
Maybe Real didn't need a change in the game, and Mbappe just can't find "his place" on the field yet. The midfield has changed the most, Kroos has retired, Camavinga is injured and Billingham also missed this match due to injury. And the combination of Vinicius and Mbappe is obviously not enough to become the most formidable attack in La Liga, I don't even remember the last time Ancelotti replaced Vinicius at the end of a match when Real needed to score, to be honest, I expected him to replace Mbappe.
Madrid have a very promising squad composition to win La Liga and the Champions League this season, but so far we have not seen Madrid show a good performance so far as the team that is the favorite to win the championship, losing several players has forced Ancelotti to make a slight overhaul in their current line-up, but as you said it seems that at the moment Ancelotti still has not found the right composition to cope with the loss Kroos, Bellingham and Camavinga, I think for now the arrival of Mbappe notyet give a significant impact on Madrid game and either because he has not been able to adapt to the Spanish league game or maybe Mbappe is too used to the easy competition so far at PSG?
In my opinion, Bellingham injury is the main factor that makes it difficult for Ancelotti to create the right line-up at the moment, because if Bellingham is not injured then I think Ancelotti will have an easier time playing him as an attacking midfielder or an attacker like last season.