My DM changed the spell “tiny hut” in my game. Is it a problem?

I am playing the wizard with the spell.

The DM came up with the idea of having strahd change the spells in my spell book, just slightly. This makes a little sense because my current character was his blood doll before becoming a PC. This serves to explain why many spell effects are actually different in Barovia.

As I said, i have the tiny hut spell. The DM asked me if it was ok if he swapped my tiny hut for a homebrew Ravenloft version. I thought it was a great idea and we talked about the specifics of the spell change beforehand and we agreed.

The spell now summons a mausoleum with a coffin and plaque for each person I want inside whether they are inside when cast or not. The walls are stone and are as impenetrable as the spell originally intended. But then there’s the door… it’s a wrought iron gate that can be seen through from either side but sound doesn’t pass through. The open areas of the gate won’t allow enemies to stab us and spells can’t pass through it. Though our swords can go through the other way and we can stick our hands out to finish casting a spell.

That all went over well with my surprised party members but the DM and I gave the door a finite HP and it got broken down by a pack of werewolves while we "fought" them through the gate. My party has mixed feelings about the door mechanic. And I can’t really say I blame them. The spell is supposed to make us invulnerable and obscured from sight.

I love the setting and random night encounters make the whole game feel more like we are in constant danger in Barovia. I worked on this mechanic with my DM because I don’t want my whole party to miss out on the experience just because I picked a spell that breaks the tension it’s supposed to have.

Is this a broken rule or should my party just accept it?