Q. The liquid in my tumbler does not stay hot/cold for long.

If your tumbler does not keep the liquid hot or cold for long, the vacuum seal might have been damaged.

If the heat insulation function between the outside and the inside is not working, condensation will form when cold items are put in, and hot items will heat up to the outside.

The cause of the damage might dent due to impact or if the tumbler fell to the ground and the impact of the fall has knocked out the vacuum seal.

Unfortunately, it is not possible to repair this.