Have you tried disabling the plugins described in https://www.akeeba.com/news/1744-advice-for-install-probs-with-march-2021-software-releases.html? Only two of these plugins should exist on your site. Disabling them should allow you to run the updates.
However, updates are handled by Joomla's extensions updater, not our code. Joomla's extensions updater has several bugs we have been reporting in private to the Joomla project for the past eight years. The Joomla project has still not addressed them. A public issue about the same issues was met with open hostility and threats against our company. Unfortunately, Joomla also forces all third party developers to use Joomla's subpar, buggy and unfit for purpose extensions updater on pain of removing the infringing extensions from the Joomla Extensions Directory. We know how to write a better updater, we had been doing that until 2014, but it is no longer allowed. So, we're stuck doing support for the issues Joomla will not address, on every single release we make.
If you are bitten by one of the many extensions updater issues please follow this workaround. Download the latest versions of Akeeba Backup and Admin Tools and install them on your site using the Extensions, Install, Upload and Install. Please try to install each extension twice in a row, without removing it before or in between.
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!