Is the instructor an ad junct? Those are cheap and replaceable. They make maybe ~1/10th of what your average FAANG engineer makes because the labor supply is extraordinarily over-saturated. Enough complaints will probably get them fired, if that's what you're looking for, but realize you're probably putting someone with no prospects and no savings out on the street and they will almost certainly be replaced with someone who gives about as many shits as you can expect from someone with a PhD who makes 30k a year. That tuition you're paying isn't flowing to the people teaching the courses.

If the instructor is an actual professor, then probably there's nothing you can do.

BTW, let your kid at least try their hand at navigating this on their own, even if you provide oversight. Barely competent people doing a poor job is not unique to pandemic times and is definitely not unique to higher ed. Knowing how to use a bureaucracy to route around an incompetent person not doing their job well is a valuable life skill. Plus, everyone involved is going to be more sympathetic to an articulate student than to a "helicopter parent".