Suction vibrators do not desensitize your clitoris, vagina, or vulva. Vibrating does not desensitize any tissue.
Vibrators can irritate, but anything that repeatedly comes into contact with your vulva is likely to do the same. It is possible to irritate the skin with any sort of stimulation, whether manual, oral or through a device. A vibrator will not permanently harm you unless you don’t use it correctly.
The good news is that it’s hard to use a vibrator wrong if you know how to use one. When using a vibrator, it should feel great, so if the vibration hurts or if it feels uncomfortable, you may wish to stop.
With a vibrator, you can’t hurt yourself unless you’re using it continuously at high speed. A word of caution: You should always make sure that your sex toy is of good quality.