I felt the same way about the battery in my 2018 MacBook ... it was losing capacity, but I didn't mind as it still ran for hours between charged.

Then it started having issues waking up from sleep. Only the OG Apple charger could wake it up, then it would see it actually had 40-60% battery but something had gone wrong while sleeping and it thought it was empty.

Intel MacBooks had terrible SMC issues, so maybe this won't afflict the M-series. Just sharing because I could still use that MacBook a few hours between charged, it just couldn't be trusted to wake up without a charger. That's really inconvenient and got me to upgrade combined with new features.

I switched from an M1 to a new M4 (this is my work laptop and it had a problem) and the old M1 has a much better battery life than the new M4. Quite noticeable. The M1 was such an awesome machine. The M4 is faster, but the M1 was plenty fast.