Update:
www.proskauertaxtalks.com/2021/02/covid-19-oecd-updates-its-guidance-on-residence-and-permanent-establishments/#page=1
www.europeantax.blog/post/102gpsc/revised-oecd-tax-treaty-guidance-as-temporary-covid-19-travel-restrictions-cont
read.oecd-ilibrary.org/view/?ref=1060_1060114-o54bvc1ga2&title=Updated-guidance-on-tax-treaties-and-the-impact-of-the-COVID-19-pandemic