Everton can win surprisingly against Crystal Palace, they were able to turn things around in the second half after falling 2 goals down in the first half. their mentality proves that they don't deserve to be relegated. Everton played very badly this season even they continued to experience defeat in the middle of this season. but at the end of the season they slowly improved to avoid the relegation zone.
It was a great escape of Everton in that match against Crystal Palace and in Premier League too. They successfully escaped the delegation zone in very last match day. If they loss it, the final match day will be a nightmare for them. I can imagine how Premier League looks like without Everton. They are not a big club in last 2 years, since the debut of Wayne Rooney but they are part of Premier League history.
I think next season Everton have to improve a lot so that a bad season like this doesn't happen again, and Everton must immediately rise to their original place in the middle of the table and become a fierce opponent for a top team.
It is what you think only. They have issue with their tactics, player mentality and more. In order to come back stronger, they have to train hard, work seriously on training field, in transfer deal tables and more. We must wait for their performance in first one or two months of Premier League 2022 - 2023 before we have evidence on whether they improve or not and what they might be able to achieve in next season.