The coffee that used to do plenty now barely registers. That's tolerance, and it's a normal, well-documented response to regular caffeine use.
Drink caffeine regularly and your body adapts — receptor sensitivity shifts over roughly 1-2 weeks of consistent use, which is why the same cup stops feeling like it used to.
The main way to reset it is a short break — even 3-5 days off caffeine tends to bring sensitivity back noticeably. Alternatively, some people cycle their intake or keep total daily amounts lower and steadier rather than one large dose, which can slow how fast tolerance builds in the first place.
A smaller, more precise format like gum makes it easier to keep amounts steady day to day rather than creeping up. Neuchu's 50mg pieces make that simple to track. You can find it here.