maintenance release of Firefox 81.0.2, which with Twitter, a workaround for which is already available last week. The problem is manifested by displaying an error about a network protocol failure when trying to open Twitter and without editing the browser code, it is solved by deleting the handler associated with the site on the "about: serviceworkers" page.
Additionally, it can be noted in nightly builds of Firefox, βTab-to-searchβ functions, by pressing the Tab key or the down arrow while typing in the address bar, switch to the search mode with the choice of the active search engine based on the characters typed, if one of the installed search engines is offered by auto-completion (for example, typing "ya" will suggest "yandex.ru", after then you can press Tab and the query typing mode in Yandex will be enabled). In addition, in the print preview mode, it became possible to change the size of the indents.
Source: opennet.ru