You definitely need to give it more than a few days for your ears and brain to adjust... it takes a good week, two, or longer for ears & brains to fully adjust to a new sound signature; new transducer medium; and/or set-up (in cases of loudspeakers and their repositioning and/or added room treatments). Certain frequencies may seem at first to be over-exaggerated; missing; distorted (excited); and/or veiled but they typically will balance out and settle down with time as your ears and brains adjust accordingly. Therefore, nailing down the true sound signature of a transducer, is extremely difficult to initially-quickly ascertain... especially with certain models and particular brands with unique house tunings.
Also experiment with fit... earbuds have their own fitting requirements... not nearly as critical as with IEMs (getting that 'seal') but nonetheless do require a proper fit in their own right as do all head/earphones really. This has been discussed, at great lengths, throughout the history of this thread (here are two examples that you might find helpful regarding "earbud fitting":
Post #26,082 and
Post #22,897. I, and many others here on this thread, would highly encourage that you to try various foam combinations to see if that improves the experience for you. Finding that perfect earbud is highly dependent on "the fit". Earbuds are prone to fitting issues due to mostly ear size but also anatomical variances between individuals. The use of foams to improve "the fit" can and does change the sound signature... sometimes drastically for better or worse and thus needs to be seriously factored in as accordingly
Personally, I always found it much easier to go between my earbuds and open back headphones than to an IEM or a closed back and vice versa. Once you figure out the best fitting/setting, with or without foams, you'll soon see that earbuds although with less bass do offer a much wider soundstage with improved timbre and separation... and via a much more comfortable, cooler, and long listening package.
Good luck and welcome to the rabbit hole!