An Issue with asset export size

Hello Comunity, I need some help, please oblige.

  I am working with a client who wanted me to resize specific icons to match the icons in the design in Zeplin I had exported these icons from Figma and sent it to them they said the size varied when they tried to put it on the website, so I added them to the design file so they can export it themselves but they seem to face the same issue I suggested exporting in SVG format but the same issue I don't know what to do they keep asking for a solution, please help me understand what I need to do to tackle this.

Thank you.