How long do you all use your toothbrushes before replacing them? I'm curious about the typical frequency.

Hello. Lately, even when I brush my teeth, it doesn't feel as refreshing as it used to.
Looking at my toothbrush, it seems like the bristles are slightly spread out.
How often should I replace my toothbrush for the best dental health?
Some people say that you must change it unconditionally before it happens, but I am curious about the criteria.
Please share any recommended replacement cycles or toothbrush care tips you have!