After the update it is not possible to edit nodes

This is due to a bad Twig release #3485956: Recursion limit exceeded with Twig v3.14.1 when editing a node or a block, they've subsequently put out a new version but the patch release included the bad one.

If you were using composer, you could update Twig yourself with composer.

To change the tarballs, we will need to do new patch releases of core. However that release should probably include #3486195: An update to symfony/http-foundation plus a trailing space took down the views UI too which is a different regression from a Symfony security release, so not immediate.

Note that installing core without composer is not really supported these days - contrib modules often need to bring in different PHP dependencies and composer is how this is managed.

#3319030: Drupal Core Roadmap for Package Manager and Update Manager will add a user interface for composer to core - so that modules and themes can be installed and updated without using the command line. Are you able to go into details about why you're not able to use composer?

If you're able to get a local development environment running, you can use composer locally, then push the results to your hosting plan (via git or whatever deployment mechanism they offer).