You still clean the tank just don't add anything else to the tank besides food and daily/weekly maintenance. Just let it naturally do its thing. Too much of a change at once will kill your betta. And let me tell you whe they say the swings can go hard in smaller tanks thats true. All I do in small to nano tanks. 2 gallon all the way to 40 gallon. Used to do big tanks bit its not challenging enough for me. All 5 of my tanks are planted and have some kind of living animal in it. Been going good for years just doing fish in cycles and letting the tanks do their thing. Just water changes and feeding.This is exactly why I stopped cleaning the tank and it bumped the ammonia level to 0.5 (however there is never any leftover food with this Betta).
I think my original issue was a bacteria bloom caused by dosing the tank with Stability and no ammonia source.
Yesterday I restarted Stability with an initial dose, I’ll continue the maintenance dose for 7 days, and keep an eye on the ammonia level.