Mixing CBD and THC products is perfectly fine, even great, because of what's known as the entourage effect. The entourage effect is the idea that cannabinoids work better together than separately. In fact, THC and CBD are a perfect combination. They're very well separated, but they're even better together.
THC and CBD combine to offer comprehensive benefits that neither could achieve on its own. While Delta 9 THC is still illegal, hemp-derived THC Delta 8 is federally legal under the law, so many purchase products with the THC analog. Many CBD users purchase full-spectrum CBD products with traces of THC Delta 9 to enjoy the benefits of the entourage effects.