I'll suggest that Math Educators SE turn off the ability for unregistered ("guest") users to submit answers.
I'm told that this is a new capacity, as of a few months ago, that can be set per-site on the SE network. Previously there was a long-standing position of SE that guest answers were always welcome (per founder Jeff Atwood's experience with coding sites, although he left SE eight years ago as of this writing); but that has now changed. See this answer for details on the recent change (note that asterisks and the footnote indicate sites where guest answering has been shut off).
It's been observed that on less narrowly technical Q&A sites (those with somewhat more subjective questions and answers), that the value of guest answers is either null or much reduced, as compared to something like the original Stack Overflow. For example, this is expressed well in a request from about 5 years ago by a moderator at another site: Can unregistered users be blocked from answering on some sites?
In our case with Math Educators SE, we have a recurring issue with one poster in particular (*) who remains unregistered with a "guest" account and effectively spams most of the questions with the same response (i.e., don't teach for understanding, just run more rote mechanical drills), and often rude comments. If and when their answers gets voted down, they can just recycle the guest account to bring their moderation back up to zero. It also prevents regular visitors or newcomers from identifying/recognizing this poster, looking at their prior history of posts, and short-circuits moderation tools such as possible suspensions or bans.
Therefore, I recommend that we turn off guest answering for Math Educators SE, as has been done for a number of other SE sites in the last several months.
(*) I'm pretty sure it's one poster, but the ambiguity itself is part of the problem here. See the ME Meta post from 2017 where this problem was asked about previously, now 3 years ago. (Thanks to Joel Reyes Noche for the reminder.)
Edit: In a comment below (and less clearly here on the main Meta site), SE Community Manager Catija has told me that I was misinformed, and this feature is not available to moderators on individual sites. I'll be refreshing my feature-request on the main site to ask for this; but at this time it's apparently not an option to activate it by the members of Math Educators SE.