[2020] Quick thinking randomly force operator back into warframe

This is not a bug. You are forced back to your warframe so that you don't lose all your energy without realizing it.  The alternative here would be that your warframe wastes all your energy tanking hits while you are doing operator things and then, when it runs out, you die instantly.  You can avoid this situation by turning off all warframe powers before using operator mode, in which case your warframe is completely invulnerable and Quick Thinking will not trigger.