It is confusing, at least compared to what we've seen before. But then again, there have been a number of errors around costuming and dialogue related to rank in previous series, too.
Pike has the two wide, one narrow that we've come to expect for captains.
Una has two wide, but is a lieutenant commander. Not sure if this is a "mistake", or a deliberate callback to TOS season 1, when they did the same thing for Spock, Finney and Giotto. (But McCoy and Scotty had one-and-a-half for the same rank.) Una had one wide, one narrow in Discovery season 2, but I don't remember if her rank was mentioned in dialogue.
Kirk is a lieutenant, and has one wide. (This matches full lieutenant from TOS.)
Spock, Ortegas and La'an are all lieutenants and have one wide, one narrow. Possibly this is a change in the system from what we saw from TOS, and it now represents full lieutenant, while one stripe is lieutenant J.G.? Spock only had a single wide stripe in Discovery season 2, and was also called a lieutenant.
Hemmer is apparently also a lieutenant, and he has two wide, like Una. This one is harder to explain, unless he is also a lieutenant commander who was accidentally called lieutenant, like Shelby was once.
As mentioned above, M'Benga and Chapel both have two wide, but AFAIK their ranks haven't been mentioned in dialogue. As
@The Wormhole mentioned, the first episode implied Chapel may be a civilian, but it's also possible she got some kind of provisional rank, similar to the Maquis on Voyager.
Ensign Christina appears to have no stripes, just like in TOS. I had thought that maybe if they bumped up each of the higher grades, they might have given ensigns a narrow stripe to differentiate them from non-officer crew, but that doesn't seem to be the case.
If lieutenant J.G, lieutenant, and lieutenant commander were all bumped up one level from what we saw in TOS, then I'm not sure what would represent full commander. They could have made it two wide, one narrow, if they had given Pike three wide.
(Also, I find the red and blue stripes hard to see, but that's neither here nor there.

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