Calendar not displaying correctly | WordPress.org

I have a problem because when I turn on the page, the calendar does not display correctly, but when I switch from the current month to the next or previous month, it displays fine. Back to the current month and it also works correctly, I use the plugin on another website and it works correctly there, I imported the settings and it also works… I tried a lot of things, but nothing helps.. Any advice? I am sending screenshots.

https://ibb.co/P4mTmT4
https://ibb.co/C1DLyXX
https://ibb.co/0rJgbjX
https://ibb.co/nMPFnbX

The page I need help with: [log in to see the link]