Three journal special issues I'm aware of on university mathematics, statistics and OR teaching, learning, assessment, support, etc. during COVID:
- Restarting the new normal https://academic.oup.com/teamat/issue/40/4
- Takeaways from teaching through a global pandemic https://www.tandfonline.com/toc/tmes20/53/3
- Responding to the COVID-19 pandemic https://journals.gre.ac.uk/index.php/msor/issue/view/93

I'm an editor for one, editorial board for another and ex-editorial board for the third. Are there any others?