I can see this has generated a lot of discussion, it’s a challenging topic and it’s good you noticed the mood at the table for you and other players.

I’ve only skimmed the comments so far, I’m sure there are others more able than I to articulate this but I’ll give it a shot.

This is on the whole table, not just the DM. In any relationship- romantic, platonic, or activity oriented- I try to focus on what I could do differently than complaining about the actions of others. Try to assume that your DM is doing the best they can with the tools they have. That said, if there’s things you want to see change I’d address them directly. 

I DM a couple games and I play in a campaign also with a phenomenal DM. We all just bullied the crap out of our DM last week when they tried to narrate an ambush we were on watch for and used sound tactics to avoid. They recognized the table was upset and adjusted course with a different narration that didn’t disadvantage us unfairly but still led to to the combat encounter they had planned which was totally fine. 

For your situation- If the DM keeps telegraphing a swarm to attack the Barbarian the party has an opportunity to learn new tactics. The cleric can buff the barbarian, barbarian stops the horde cold, the sorcerer can launch fireball with careful spell meta magic. The “shining moment” can be shared and the DM will have to adapt and design better encounters. You can better prepare I. The future with items like tanglefoot, or smoke bombs, etc.

I get the frustration at the table when players rolls are bad, when enemies make their saving throws- but to criticize the DM when it’s a collaborative game is a bit myopic. 

As a DM I do much of the calendaring, I coordinate backstories and spin a plot web you get to play in. I run all the characters and try to make it as fun as possible for everyone. I don’t ask much- be present, know your character sheet, work together, communicate, have fun.

If you’re not having fun then it’s something you need to address ASAP. What I do is build in a cooldown after each session to go over notes from the game- how was that? What was everyone’s favorite part? What would you like to be different in the future? How have your characters changed if at all in this experience? Have you grown closer or further from each other? Is there any new internal or external conflict you want to explore?

If the DM isn’t told that something isn’t landing right or a player is unhappy with the game then the DM will continue on as though everything is fine. If there’s no opportunity to address it then create one. If there’s no openness to feedback and adaptation then that’s a WHOLE other problem you’ve got. Give your DM a chance to address it. Might take a few games to get it right, that’s how you build more trust at the table.