It may leak, but tough, why are you using it for warm drinks?
You can't put hot drinks, in the travel mug. You have to wait for them to be at drinking temperature, so don't use in a hurry. If they leak, expect SHO to debate and demand videos and then still not replace or refund. Found my Waitrose reusable cup, far more reliable and it didn't mean I paid £22 for a landfill item.