The 5e rules state “object”, but various others sources and rules just clarify they change shape.

Most mimics don’t chat, so these mimics are clearly a little more sophisticated.

Plus this is a golden lady, which seems more object-like (statue) than person like.

I think it’s fair.

As the party cleric, “Heal me” is met with “I shall avenge you!” and magic all around.

You want healing? Pray to your own God.

Tripod.

They get an extra foot.

It’s bulletproof not soupproof.

Let’s say you want to haggle a better price at a shop.

You can start by explaining that to your DM.

They might ask how, and you can just generally describe what you’d like to do.

Not sure how to explain? Ask the DM to better describe the shop or individual.

Then pick something, maybe they have a sweet hat, or a cool earring. Maybe the store looks really clean or maybe all the other patrons are dressed fancy. Maybe you can investigate the craftsmanship of the weapon or shield and compliment the shop owner.

The important thing is you pick something, it doesn’t matter what. Maybe that earring you commented on is a family heirloom. Roll well and the shopkeep is reminded of their family an gives you the family and friends discount. Roll poorly and the shopkeep is reminded of how their family was brutally murdered and they ask you to leave.