That first Apple silicon M chip was a game-changer.
The physical cores and other improvements in the M4 don’t seem substantial enough to justify the cost of an upgrade -- at least not for my needs. The jump from 8GB to 16GB RAM in base models is notable, but for my personal use - photo/video editing, music production, and work - the M1 is still more than sufficient.
And you - if you're satisfied with your current M1 Mac mini, there's little reason to rush out and get the M4 model. Save your money and keep using a device that still meets your needs. Apple's silicon platform has matured to the point where older models remain viable for a substantial period.
However, if you’re new to the Macs and considering a switch for work or personal use, now is a great time to jump in. Get an M4 Mac mini.