I don't how Grosjean has stayed in F1 for so long. On a good day, he's mediocre, on a normal day, he's a disaster. He's involved in so many incidents, and his performance is not good enough to warrant his seat.
Apparently he enjoyed the lockdown, spending all the time with his family, cooking and the like. Wouldn't surprise me if this is his last season and he stays at home from the end of the year and writes more cook books with his mrs.