I have the exact same code in production and sandbox. Things look as expected in sandbox, but in production I can see different css being applied. In Production the lightning input field is being rendered with a class of slds-form-element_horizontal. That class isn't applied in Sanboxes though.
<template> <lightning-record-edit-form record-id={contactId} object-api-name="Contact"> <div class="slds-grid"> <div class="slds-col slds-size_2-of-12"></div> <div class="slds-col slds-size_3-of-12"> <lightning-input-field disabled field-name="FirstName"> </lightning-input-field> </div> <div class="slds-col slds-size_3-of-12"> <lightning-input-field disabled field-name="LastName"> </lightning-input-field> </div> <div class="slds-col slds-size_4-of-12"> </div> </div> </lightning-record-edit-form> </template> 