Napisano mi w czym tkwił problem. Tutaj jest komentarz hostingodawcy:
I managed to find the culprit of this issue, which happens to be astra-sites.
No worries, though, I have fixed the issue for you, I used the following solution.
Disabling astra-sites before updating/installing the plugin(s): wp plugin deactivate astra-sites.
Alternatively, can use this command: wp plugin deactivate astra-sites && wp plugin update –all && wp plugin activate astra-sites.
It will deactivate astra-sites and update all plugins before reactivating astra-sites again, which is useful in case you have multiple updates that you wish to execute.

Na szczęście zrobiłam backup wcześniej więc szybko przywróciłam stan strony do tej sprzed problemu.