But the whole damn GOP is afraid of Trump, even after many of them spoke out against him in the 2016 election. They weren’t afraid of him then, but they kowtow to his every whim today.

That’s not doing your job as a member of Congress. That’s being a toady to Trump.

I mean...maybe?

The job of being a Congresscritter involves a lot of different, sometimes contradictory things.

One of the main functions is to be a representative (literally, in the House). You're there to represent your constituents, and to be the voice in Congress for what they want. Most Republicans don't want their representatives to be speaking out against Trump. They like what he's doing. They support his proposals. They don't mind when he does things that violate the Constitution (either because they don't believe they are violations or believe, like man other folks up and down the spectrum, that the President should fight fight fight on their behalf and let the Courts stop him if he goes too far rather than bargain against themselves). Generally speaking, speaking out against the sitting President is the job of the opposition party, not the President's party. Most GOP Congressbeings are from districts/states where most of the people don't want their representatives to be attacking Trump, or weakening him for other fights.

One of the other functions is to advance policies you think are correct, regardless of whether they are popular. But that function does not necessarily involve disagreeing with the President in public. The President has not had his every whim kowtowed to. The filibuster still stands, the ballroom remains unfunded, almost no Congressional funds were successfully impounded, Congress hasn't created the tariff power he sought to wield, he's had record numbers of nominees (most recently Casey Means) have to withdraw, he's had to change his personnel in response to unhappiness on the Hill, etc. He's gotten virtually no legislative agenda, and had some losses even outside the legislative agenda, because of the GOP in Congress QUIETLY refusing to go along with some things.

One of the other main functions is political. You do things that are performative. You bring bills to the floor that can't pass in order to help your party, or hinder the other party, or put pressure on the Administration, or demonstrate where you are to your supporters. Again, though, it is usually not the job of the President's party to do these sorts of things against the President. It's the opposition's job.