I just moved into an apartment and the shower does not drain well. It floods above my feet every time i shower. I've tried running vinegar down it after showers and this sort of helps, but eventually i need to use a plunger on it to get it to drain, since it will stop draining entirely after a few days.
I have one of those that I have to unscrew then unscrew the drain itself, notice the hairs on the cross bars as you remove the drain assembly. Don’t break those hairs just unscrew the lower section and lift it up. What you wipe probably find is a wad of hair and soap scum. YUK! My wife daughters and most of my grand daughters have long hair, when they shower some goes down the drain so I have to do this several times a year. I haven’t needed a snake and you might not either, it is gross but only takes a few minutes. My drain has an o-ring seal but in the past I had to roll a bead of plumbers putty to seal the flange when re installing. I have a wrench to pull the flange but have used heavy duty needle nose pliers in the past. I would recommend pulling it out with this method because a drain cleaner won’t dissolve the entire hair ball and it may break loose and lodge lower in the plumbing and then a snake would be needed. Give removal a try , it’s gross but usually works.
That is a push-to-close drain stopper. It will toggle between closed and open if you push on it. Many of them can be removed by a firm pull. It will have some sort of spring or rubber retainer.
Likely that your shower has a hair clog. Pull the stopper out and see if you snake it. They have cheap plastic drain snakes out there these days.
Vinegar is a mild acid. Good for salad dressing. Doesn't do much for hair clogs.
Vinegar + baking soda = acid + base - good for grade-school volcanoes and can help a little with hair clogs, but not that much.
What really works on hair clogs?
A plunger is sometimes enough to push the clog through, but since you have already tried that and the problem occurs again fairly quickly, that isn't clearing the entire clog.
Chemicals. Two basic types, loosely categorized as "enzymes" and "nasty stuff". The enzymes are good for periodic use to help keep the pipes from clogging and for mild, partial clogs. The nasty stuff is good for complete or nearly-complete clogs, though I'd be lyeing if I said it was a perfect solution.
Snake. This can range from a single-use plastic strip to a small handheld snake to a larger snake that can be used by hand or with a drill (my personal preference lately) to a "big" rented machine. The big machines are normally only needed for main drain cleanouts with roots or other really bad problems. For an individual tub or shower, you don't need (and in fact, would have trouble using - they're just too big) a big machine. I usually use something like the RIDGID PowerSpin:
Whatever you do, get some heavy-duty gloves. Drain cleaning is messy, no matter how you do it!