Could be a confluence of factors. Many mentioned above, plus:
1. ESPN went all in on their coverage of the NCAA Women's Basketball Tournament. Since they didn't have broadcast rights to the Men's March Madness they promoted the hell out of WBB on tv, on their web site, and on social media to the point where it drowned out their own (minimal) promotions of wrestling.
2. Moving coverage to ESPN+. The trend might be towards streaming, but a lot of wrestling fans skew older and many prefer to watch on TV. ESPN turned their backs on an entire segment of viewers by moving the full mat coverage off of ESPN3 and onto Plus. Additionally many younger viewers and former cord cutters are now economizing with their streaming. There are too many streaming platforms out there, killing you by a thousand papercuts, so people are making tough choices with their streaming subscriptions or resubscribing to cable.
3. Brick challenges. This is more long term, but the reviews are ridiculously long and extremely disruptive to the flow of matches. It's easy for people who watch live to get turned off by all the dead time during reviews, and instead catch the replay or highlights. NCAA needs to fix this before more fans are discouraged from watching (or attending) live wrestling matches.