I don't have any issues with creating a post but it's the accessibility of the reactions that seem to be reduced.
Maybe I can clarify what I was describing a little bit. There are issues with both the "How are you feeling" part of writing a post, and giving a reaction to somebody's comment on one of my posts. They are not the same issue.
With the How am I Feeling part when I write a post, it has a list of about 120 predefined options, with the list usually starting with Happy and continuing with feelings like Sad, Angry, Goofy, Cute, Confused, Meh. If I wanted to say I was feeling something not in that list, such as flamingoed, I could type that in the search box, press the search button and it would appear as an option that I could select and my post would say I was feeling flamingoed. Now there is still a search box, but that only seems to filter the list of 120-or-so pre-defined feelings. If I type chill into that search box, all other entries in the list are hidden and I can select chill. If I type flamingoed then nothing at all appears where the list previously was, but there is no way to select flamingoed as my chosen feeling.
The other reaction is when people have commented on a post I have written. The only reaction I seem to be abel to give is to Like it. It used to be possible to react with Like, Love, Care, Haha, Sad and angry. When somebody else writes their own post, it is indeed possible to react with those options (though angry seems to be off the menu now). To react to somebody else's post there is a Like button and then a link for Other Reactions, which is that list. when I write a post and somebody comments, I can Like it, but there is no Other Reactions option. Often one of my friends will comment something humourous, and I want to react with a Haha, but have to react with Like and then comment Haha.
As with all Facebook changes, usually things that aren't working correctly get ironed out within a week or two. In case it's not something that Facebook has messed-up for screen reader users, I'd love to know if any NVDA users have figured out how to do these two things :)