Why that IMG_8558.heic suddenly became 2.8 MB bigger after using iLoveIMG

https://thedatascientist.com/heic-to-jpg-converter-best-worst-options/

Why some web converters, like iLoveIMG, yield much larger JPEGs You uploaded IMG_8558.heic and expected a tidy JPEG. Instead you got a file that is 2.8 megabytes larger than outputs from other tools