I mean, I don't think it's anything to be upset about. I just think that framing this as fixture congestion when you're mostly using players who aren't playing in the CL/EPL is silly. For example, I don't think Arsenal is worried about fixture congestion for Ozil or Smith-Rowe or Martinelli or even Nelson and Willock. It also gave Tierney/Holding/Bellerin some game time, which is a plus. I'd be perfectly happy if Arsenal ran the following out against Liverpool, and wouldn't be even slightly concerned about fixture congestion for any of them, assuming the backline trio is still not fully fit:
Martinelli
Nelson - Ozil - Smith-Rowe
Burton - Willock
Tierney - Mavropanos - Holding - Bellerin
Martinez
Have John-Jules, Balogun, AMN, Medley, Macey, Bola, and pickamidfielder on the bench.