If you need access to your calendar from time to time when you are not connected to the internet, Google Calendar’s web interface will be a little more useful. When Google implemented a new user interface for the app in 2018, it meant that you removed the ability to access the data in your browser without an internet connection.
Google now notes on the Workspace Updates blog that the feature is back, but individual users will need to enable it – the instructions are available here. If you do not see the option yet, check back later, it starts over the next 15 days or so, or it may have been disabled by your administrator. In the blog post, access is only mentioned for Workspace accounts (formerly known as G Suite), but the support page has no restriction, so we’ll see if it comes to individual free users as well.