The Los Angeles Chargers vs. Arizona Cardinals Monday Night Football game did not do well in terms of viewership, to say the least. The Chargers-Cardinals tilt drew just 1.8 million viewers on the ESPN+ platform, per Pro Football Talk, which is the least-watched game (that the NFL and its broadcast partners have publically announced ratings for) since 2008.
You have to go back to 2008 to find the last time NFL ratings were so low. That was when, ironically, the then-San Diego Chargers took on the Oakland Raiders and blew them out 34-7. That matchup was the last time an NFL game officially had under 2 million viewers. That said, this Chargers-Cardinals game may not be the least-watched since 2008.
The league has never released the ratings for the 2023 ESPN+ Jacksonville Jaguars vs. Atlanta Falcons Toy Story alternate broadcast nor the 2017 Baltimore Ravens-Jaguars game that was exclusively on Yahoo.
Why were the NFL ratings for Chargers-Cardinals Monday Night football so bad?

There are several factors that went into the sub-2 million Chargers-Cardinals Monday Night Football viewership numbers.
First, there are the football reasons. The Chargers are 3-3 on the season and the Cardinals are 3-4, so neither team seems like a Super Bowl contender. Plus, the Chargers and Cardinals have two of the smaller fan bases in the NFL.
On the broadcast side, this game was overshadowed for two reasons. One is that it was the third time this season that there were two Monday Night Football games going on simultaneously, and the Ravens vs. Tampa Bay Buccaneers game was a far better matchup. Plus, that game was on normal television, while the Chargers-Cardials was on the streaming-only ESPN+ platform.
While all these reasons add up to a reasonable conclusion, the outcome is something the NFL can't be happy about. As the league tries to tweak its traditional weekly schedule and add new platforms, it seems as though there is a limit to when and where the national football-hungry audience will watch.