Concerns:
About two years ago the plant had very firm, glossy leaves and was growing a lot.
Here it is now:

Darryl
Thanks for sending the photos and sharing your care details.
If we take a closer look at this leaf…
It’s looking very much like a thrips infestation – a closer look will confirm it (I’ve circled the thrips larvae)

Other than the infestation, based on what you’ve written about your care, here are some pointers:
- You absolutely should be using fertilizer otherwise your plant will have but one or two leaves per vine – more info here on fertilizing
- The light levels, in my estimation, if I were to measure them where this Monstera lives, would probably be in the 100-200 FC range, which is quite low for a Monstera this size; putting the plant closer to the window or closer to a larger window where the indirect light levels are in the 200-400 FC range would be better – more info here on measuring light
- Misting is not necessary – do it if you like to but don’t if you feel obligated as it has no impact on good growth (light has the biggest impact)
- The dark brown dry patch on the newest leaf is indicative of mineral build up in the soil from a lack of flushing, which is the result of only pouring small amounts of water into the soil and bottom watering; thoroughly top watering and flushing (pouring through more water beyond the point of saturation and allowing it to drain away) are necessary to prevent leaf damage from mineral build up
If you want to develop strong fundamentals in plant care (like understanding light), my book and online course will guide you in the right direction – instead of useless tips and tricks (like misting and bottom watering).