Yes, it is perfectly normal for kombucha to form a cloudy or jelly-like substance at the bottom of the jar. This is a healthy byproduct of the fermentation process.
The cloudy or jelly-like substance you see in your kombucha is called a SCOBY (Symbiotic Culture Of Bacteria and Yeast). It's a natural part of the kombucha fermentation process. As the bacteria and yeast consume the sugar and tea, they produce cellulose, which forms this visible mass. The SCOBY is a sign that your kombucha is fermenting properly and is full of beneficial probiotics. The amount of SCOBY formed can vary depending on factors like temperature, sugar content, and the strength of your starter culture. Don't be alarmed if you see strands or sediment floating in your kombucha either; these are also normal byproducts of the fermentation process. They are harmless and can even be consumed. The SCOBY at the bottom is often referred to as a 'baby' SCOBY, as it's a new layer forming. You can remove it, leave it, or even use it to start a new batch of kombucha.
If you find the sediment or SCOBY texture unappealing, you can strain your kombucha through a fine-mesh sieve or cheesecloth before drinking to remove the solids. This won't affect the health benefits of the kombucha.