Really loved Bootstrap when it came out, but nowadays the style and its way of doing things feel a bit dated. That said with the current (good) state of CSS in browsers you can build your own responsive designs without relying on a framework.
A negative effect of all these frameworks is that I work with more and more frontend devs that just don't know their way around (S)CSS, so if you throw them into a project that uses a framework they don't know or (gasp) hand-crafted CSS they are completely lost. Same thing with Javascript tooling btw, in a recent project a frontend dev wanted to rewrite the whole codebase because he was not familiar with Webpack and only knew vite (which is the new cool thing it seems), so he wasn't able to work with the existing code.
A negative effect of all these frameworks is that I work with more and more frontend devs that just don't know their way around (S)CSS, so if you throw them into a project that uses a framework they don't know or (gasp) hand-crafted CSS they are completely lost. Same thing with Javascript tooling btw, in a recent project a frontend dev wanted to rewrite the whole codebase because he was not familiar with Webpack and only knew vite (which is the new cool thing it seems), so he wasn't able to work with the existing code.