Home doppler safety

I have been using my home doppler for awhile now. I purchased it when I was 9 weeks pregnant and am now 18 weeks. I do not use it every day but I have used it often enough. I now found this online and am freaking out!! Anyone have any insight as the whether this is true or not? 😭

I have had 4 ultrasounds so far and will be having my 5th next Saturday! I had a hemorrhage on my uterus that needed to be monitored. I’m just so worried now!