When your cat purrs, it's usually a sign that they're content and happy. However, sometimes a cat will purr when they're feeling anxious or stressed. This is known as low purring.
Low purring is a way for your cat to self-soothe and calm down. It's similar to how humans might hum to themselves when they're feeling tense. If you notice your cat low purring, it's a good idea to give them some extra attention and reassurance. You can do this by petting them or speaking to them in a soothing voice.
If your cat is prone to low purring, there are some things you can do to help them feel more relaxed. Make sure they have plenty of places to hide and escape to if they start feeling overwhelmed. Provide them with lots of toys and playtime so they can stay active and mentally stimulated. And try not to put too much pressure on them - let them approach you on their own terms instead of forcing interactions.
By understanding low purring, you can help make your cat's life happier and less stressful.