Weather is THE factor……actually light. If you have noticed, your bamboo probably does best in really bright extended light. Mine is doing the same thing. But, as a master gardener, I am just trying to pull it through til spring when it will get light for longer periods each day. Also, keep it watered and make sure it is not too root bound…..good luck

I think you water it too much.

In most plants, I'd say they'd received too much water - but it's just about impossible to drown a bamboo! While it shouldn't be exposed to direct sunlight, it does need bright light to grow, so it may not be getting enough light. You may also want to be sure that it's in an area that's warm, as bamboo is essentially a tropical plant. You might also consider giving it an occasional feeding with a liquid fertilizer mixed at about 1/4 the usual strength on the label. Good luck!

indoor bamboo has to be fertilized every few months, just add some regular Miracle Grow, regular plant formula. to the water, a half a teaspoon should do fine, then every few months add a bit more.

weather could be a factor however you did not mention where you are now