Well excuse me for saying this, but it sounds as if you're talking out of your behind right now and just going by 'what you feel'. Carpet did have an impact on both of them, but it's pretty miniscule for Novak and not that big for Fed either.
1) I already showed you Novak's carpet record. It was lower than his average percent, but because of the few times he played there, it didn't impact his percentage that much. Without carpet, Novak goes from 78,5 to 79,1. Without carpet, Fed (who played 4 times as much on carpet, but also had a better winning percentage (75,4 vs. 71,4)) moves from 81,0 to 82,2 %.
2) Federer did have a poor 2013 indoors, he went 11-5, a win percentage of 68,75 %. Removing 2013 from Fed's indoor record would spark his percentage up to 81,6 % for his entire career - i.e. half of the lift that carpet gave him.
But count it as part as his post turning 31 years and my gut feel would be, that it's enough to pull it down. However, having checked, it turns out my gut feel was incorrect. While he did have a poor 2012-2013 (71,0 % in total), his excellent 2014, 2015, 2017 and 2018 campaigns more than make up for it, so overall he's 64-12 = 84,2 % indoors post turning 31. You're welcome.
p.s.
Counting from 2002, Fed's win % is: 221/259 = 85,3
Counting from 2003 it's: 197/228 = 86,4 (more or less identical with his overall record from 2003 onwards)
In other words: Just like his overall record, it's his first so and so years that hurt his percentages. That includes carpet, but carpet isn't the main explanation as his carpet record was just as good/just as poor in his early years as his overall indoor record (68 on carpet, 67,5 indoor up until 1.1.2003) and he didn't play that much on it (see how much removing carpet means for his percentage above).