Per Ethan Anderton on SlashFilm, quoting Bill Hader:

“Right when the lockdown happened in March, we were a week away from shooting. So the last time I was in a room with a lot of people was the table read episodes one and two of season three, and we were ready to go. Then it all got shut down. Season three is completely written, ready to go, and then during this time we actually went and wrote season four. So we have both of those kinda done. We’re just waiting until we can start shooting again.”

“Barry” is a  sui generis example of peak TV. It takes a lot of risks in terms of both plot and tone, and so far they have all paid off. I certainly couldn’t predict how Bill Hader and Alex Berg were going to write their way out of the end of Season 2 of “Barry,” but I guess they cracked it and then some.