hope that everyone is doing well . I have just started to practice Kundalini Yoga, however, sometimes I have to stop my practice due to nausea. I practiced ashtanga for 2 years, without any problem. I was wondering if the nausea was a usual side effect for someone just beginning this practice. Thanks for your help.

Nausea during yoga, although sometimes related to improper breathing, usually is a side effect of the cleansing process KY sets forth. If you're doing Kundalini it includes a lot more of pranayama and uses a lot more movement, which will produce stronger cleansing effects than more tranquil forms.
Be sure to drink plenty of water after your yoga session, to help the kidneys process all the junk that is being released from your organs into your bloodstream, and take a look at your lifestyle regarding diet (should you change it?), drinking (too much) coffee, etc.

How cool that you are trying a new type of yoga! Perhaps your body is just going through a transition. Be sure to hydrate and maybe try to keep incorporating your astanga practice as well.

Hanuman

I think that’s normal because you are getting more into your gland system and using more powerful breath practices. Don’t worry, with practice it will get easier! If you start to feel sick, just stop and close the eyes. Only do what your body really wants!

SamLA