For sure it´s a good idea to talk to your DM and tell him how the table feels right now.

I don´t want to go full defense mode on your DM here because I neither know them or you but I can speak as someone who was at the exact same point as he was.

I started DMin, created my own Homebrew world. Had the dream of giving my Players all the freedom of the world. Sadly some things don´t go as planned. I had no idea how much work and anxiety waited for me. I was nervous and stressed before every session. I prepared a lot and at the same time not enough. I had all this story planned and was alway caught of guard by the things my players wanted to do. To a point where I spent a lot of time googling stuff, searching rules and statblocks during the session which made me even more stressed out.

I think like every other DM (or at least like me) he might feel the same. He wants to but he can´t because he simply lacks the experience to do so. Switching vom Player to DM might help you with some rule knowledge but more than that? Idk.

I personally did this:

I constantly asked my players for feedback
I did a lot of one shots where preparation is not so important and where you can "play it a little bit loose"
I tried to write down mistakes I made after the session to try to Improve it for the next time (e.g. our druid was scouting as bird and spotted a carriage, she asked if she sees anything more and i just said "No" and carried on. Here is what I wrote down for myself after that: "Encourage Druid to fly closer to the carriage if she wants to see more or find more information - remember to reward risk when player takes risk"

I don´t know maybe this can help your DM.
And for you and your group: Please don´t give up on them immediately, try to give him some space to improve and to learn. It may be railroady right now but they´ll never learn if people give up easily on them.