I can confirm YouTube is behind this problem because I watch YouTube on different browsers on 3 different phones and they all suddenly (in the last 3 days) staying in portait mode when I tap full screen.
I have to activate auto rotate, rotate phone and click full screen and disable auto rotate , and then rotate phone. (For side sleepers 
haha.
Im having the same issue on Brave, Chromeand even on duckduckgo. Youtube app itself seems fine. Could be a chromium issue. Hopefully gets fixed soon as this is so frustrating.
@Team_metaverse @ Brave Support Team:
Can you please resolve this issueā¦ 
itās so important for all those who use Brave YouTubeā¦ and I spend more than 50% of my daily screen time on YouTubeā¦ now waiting for you to resolve this minor issue or switch to alternative browserā¦ YouTube horizontal full-screen auto-rotating in vertical modeā¦
Hello brave teamā¦
Pls resolve this issue
This issue happens on Google Chrome as well. This means Brave team canāt fix it, because Chromium has the issue in fact.
Same here since yesterday 
For everyone encountering this issue, it does appear to be an upstream issue, meaning that the bug will have to be fixed in the Chromium engine and weāll have to wait for that.
Will update if I have any further information.
I am having some problems 
I got the same issue 
Glad somebody else noticed, I hope this getās fixed, auto rotate is a total PIA.
I have the same problem.
once again my hatred has increased
I suggest to consider a youtube-specific hack to fix this. This may not really be a bug, but a change in behavior which Google is happy with, since it pushes users to the youtube app instead of the webpage.
I just checked, and when I go to Rumble, using the exact same browser, I get the old behavior of showing the videos in landscape.
Since watching youtube without ads is a killer feature of Brave, I suggest to consider a hack to fix this without waiting for an upstream change (which may never come).
I opened an issue here: https://github.com/brave/brave-browser/issues/36825
Have you checked any other site besides Rumble? Because for me, sites like vimeo and dailymotion donāt rotate as well, but surprisingly Rumble does. Maybe Rumble saw that ābugā and fixed it on their own or something idk
Does someone know how to post in the chromium discuss group? I sent a message last week, but I still donāt see it in the group. When I posted it it said that it could take a while due to moderation, but It has been a whole week. I canāt even find the message anymore which is still pending to be posted.
There was an update and guess what? This issue is still here and ig here to stay unfortunately
The issue just isnāt fixed yet ā please refer to my previous reply:
Actually chrome for me updated the day before and i thought it would be it. Unfortunately not? Hm
Same problem. Please fix this ASAP.
