Turn on a multi-functional pressure cooker (such as Instant Pot) and select Sauté function. Warm olive oil for 3 minutes. Add onion, carrot, celery, and garlic. Cook until onion is soft and translucent, 4 to 5 minutes. Season with cumin, coriander, turmeric, salt, white pepper, fennel, and chili powder. Cook for 2 more minutes. Stir in tomato paste.

Pour in broth and water. Stir in lentils and squash. Crumble bouillon cube over the top and mix well, scraping the bottom of the pan to remove any browned bits. Cancel Sauté mode.

Close and lock the lid. Select high pressure according to manufacturer's instructions; set timer for 8 minutes. Allow 10 to 15 minutes for pressure to build.

Release pressure using the natural-release method according to manufacturer's instructions for 10 minutes. Open valve to vent remaining steam, about 5 minutes. Unlock and remove the lid.

Mix in lemon juice and toss kale leaves just on top of the soup. Replace lid and allow kale to steam for about 5 minutes. Remove lid and adjust seasonings, if desired, before serving.