Online doesn't mean that you have unlimited capacity for students. You still need to grade homework and exams, offer virtual "office hours", answer emails.
The school where I earned my master's degree had two programs, one online and one in-person. There were several differences, but the most salient one was that the in-person program conferred an academic degree while the online one conferred a professional degree, and the online one had significantly higher tuition.
The fact that many state universities have policies limiting how rapidly academic degree programs' tuition can increase, but not the professional ones, is, I assume, just a coincidence.
But all of the above can be done by TAs, and do not need a professor. Professor time is much more limited.
My university had a course where an external professor would deliver a mixed online/offline course. Videos were available on institute website. Professor would hold a class every week to go through that week's contents and clarify student doubts.
This saved a ton of effort on the professor's part.
There is a reserved scheduled class room for the class, but there is no organized zoom meeting yet (or maybe not use zoom after all?).
There is a mail box to drop of home work assignments, but nobody has figured out where students should email things for grading (the prof, the TA or a function account?).
The prof has a set of notes that (s)he writes onto the white board, but not a set of slides to be emailed out. Or might have electronic slides, but they contain annotation that should not be sent out to students.
Everybody has to figure out how to make sure that 200 students can join the zoom session, but have their mic muted. And know how to unmute when they want to ask a question.
Exams for the mid terms might be printed but now need to be (e)mailed. And how do you prevent cheating in an exam that was meant to be taken under supervision with pen(cil) and paper only. Of course you can create an open-book exam where google doesn't help, but that is extra effort. And does not prevent collusion between students.
Somebody need to figure out how to replace lab courses.
And the list goes on. All of that can be fixed. And after a couple of semesters an online class might be no more (or possibly even less, but that is not proven) work than the current offline course. But switching in the middle of a semester with ideally no downtime IS a lot of extra effort.
I'm honestly not sure what you do at this point. Finish up the semester as best you can and just give everyone a Pass? Force people to attend a summer session whether or not they can afford to not be working? There aren't any good options.