A green tint, a black frame with sound, or a picture the wrong way up is nearly always a rendering problem on the device you are holding — not something wrong with the seller's broadcast.
The giveaway: if the chat is moving and the bids are updating, the stream is fine. You are receiving data; your device is drawing it wrong.
The three fixes, in order
1. Close the tab and open the show again. Fixes most of it. Video decoding goes wrong once and stays wrong until the player is rebuilt.
2. Switch browser. If you are in an in-app browser — opened from a WhatsApp or Instagram link — get out of it. Those are the worst offenders for video, and opening the link in Chrome or Safari directly solves a surprising share of these.
3. Restart the phone. Genuinely. A wedged hardware video decoder is a real thing and this is the only reliable fix for it.
If it is upside down or sideways
That is the seller's camera orientation, not your device. They are the only person who can fix it, and they usually do not know — the preview on their own phone can look right while the outgoing stream is rotated.
Say so in the chat, once, politely. "Video's sideways for me" is useful information they cannot get any other way. If several people say it, they will fix it mid-show.
If it is black with no sound at all
Different problem — that is a stream that has not connected rather than a rendering fault. Look for Reconnecting… or The host is reconnecting: if you see it, the seller has dropped and the auction is still running. Stay. How to join a live show.
What you do not lose while fixing it
Nothing. Bids live on the server, not in the page, so closing and reopening loses no bid, no position and no place in the room. If I leave the show, do I lose my bid?
The one thing not to do
Do not keep bidding on something you cannot see. The bidding keeps working when the picture does not, which is exactly the trap: you are buying a thing you are not looking at. Fix the picture first, even if it costs you an item.
More: video is buffering, the seller is answering things before I see them, what you need to watch a show.