Home Doppler heating up baby?

B

I got a home Doppler at 10 weeks and found baby pretty much instantly and have found baby instantly every time I’ve used it so I only use it for a second. Once a week I’d say since getting it. I record the sound on my phone so that way when I want to hear baby I can play it. Today I had that weird mucus plug looking thing fall out of me so I decided to ease my mind with the Doppler, it definitely took me a while to find baby bc I guess baby has moved up a bit from where it’s always been! So I tried about 3 times to find baby. Someone just messaged me on social media saying that it can heat up my baby and bad things can happen? So now I’m of course freaking out about this since I did have to really search with the Doppler today on my belly. 😭 is this true?