Is it just me or does the game runs very sluggish and slow on steam deck?

I think I'm right before fighting the final boss. However I still have not found a way to get through the weird barriers. Can anyone point me in the right direction?

What do I need to do in order to get that? The description is kinda vague - "Beat the game after finding everything". What does "everything" mean? I have already 100%-ed the whole map and visited every room. However, I still didn't get the achievement even after beating the final boss twice. What am I missing? (Do I need to buy all the shop items?) *Edit:* So it's not the shops - bought every single item from there and beat the game again. Same deal. Is it maybe the Astral Gates? Do I need to complete ev...

All the music and sound cuts out, and does not come back, unless I restart the game. Which is quite annoying because of this other bug: https://steamcommunity.com/app/2463220/discussions/0/690871474424153659/

Hi, I completed the map 100%, did all the quests, bought out every shops, but I'm still missing a single starshard. Any idea where it could be?