A plugin we built uses a bunch of settings that entered into an ACF options page. This was throwing errors with the new update, however. So I followed the suggestion on the 5.11 update page and replaced those with get_option(), but I kept getting false when I used the same ACF field name that I was using previously with get_field().
I checked phpmyadmin to see if the options entries were still there, and noticed that the ACF entries are saved in that table with the prefix options_. This fixed it for me!
You might want to note that prefix in the options table for developers replacing get_field() with get_options() for any options saved in an ACF options page!