Yes, headphones with less punch than your previous pair are notoriously hard to adjust to. But, every time you're listening you're adjusting to them

Other people post on here to say how bad their first real headphones are because the sound signature (balance of bass, mids and treble) is different than their gamer headphones and they assume the headphones are garbage

You also need time to get used to hifi

You can't make that big an upgrade and change in sound signature without needing to invest some time with them and it seems like you can intuitively tell that.

On the volume issue, your computer needs to work twice as hard to drive them because of the 80 ohm impetus. A cheap headphone amp would solve that problem if it's a big deal to you. They use juice from the outlet to deliver a high enough charge at 80 ohms to drive them.

Welcome to the best hobby my friend