[Desktop] Mixed hidpi multimonitor fullscreen video player issues

[Befo]

Description

Opening the video player to a fullscreen view while the browser is placed on a 1080p screen (lower res monitor, with the other being a hidpi one) of a mixed hidpi multimonitor setup ends up in the video being cropped and off-centered, as if the browser could not properly capture the correct dimensions of the display and with the control hud of the player no more receptive to the mouse.

Steps to Reproduce

1. Open Brave Browser in the lower res monitor
2. Navigate to a video
3. Start the video and set the player in fullscreen mode

Actual result:

Expected result:

I can see the video properly sized with the player hub working properly

Reproduces how often:

Reproduces each time apparently regardless of where the browser has been opened first or if it is running in the other display.

Brave version (brave://version info)

Brave	1.13.82 Chromium: 85.0.4183.83 (Official Build) (64-bit)
Revision	94abc2237ae0c9a4cb5f035431c8adfb94324633-refs/branch-heads/4183@{#1658}
OS	Linux
JavaScript	V8 8.5.210.20
Flash	(Disabled)
User Agent	Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.83 Safari/537.36
Command Line	/opt/brave.com/brave/brave --enable-dom-distiller --disable-domain-reliability --no-pings --extension-content-verification=enforce_strict --extensions-install-verification=enforce --origin-trial-public-key=bYUKPJoPnCxeNvu72j4EmPuK7tr1PAC7SHh8ld9Mw3E=,fMS4mpO6buLQ/QMd+zJmxzty/VQ6B1EUZqoCU04zoRU= --sync-url=https://sync-v2.brave.com/v2 --enable-features=MixedContentSiteSetting,WebUIDarkMode,DnsOverHttps,OmniboxContextMenuShowFullUrls,AutoupgradeMixedContent,PassiveMixedContentWarning,PrefetchPrivacyChanges,PasswordImport,ReducedReferrerGranularity --disable-features=TextFragmentAnchor,VideoPlaybackQuality,AutofillEnableAccountWalletStorage,AllowPopupsDuringPageUnload,NotificationTriggers,PasswordCheck,AutofillServerCommunication,PrivacySettingsRedesign,SafeBrowsingEnhancedProtection,TabHoverCards,SmsReceiver --flag-switches-begin --flag-switches-end
Executable Path	/opt/brave.com/brave/brave
Profile Path	/home/alessio/.config/BraveSoftware/Brave-Browser/Default

Version/Channel Information:

Current stable channel.

Other Additional Information:

I have not tried with Chrome, but I cannot reproduce the issue with Firefox.
Multimonitor setup: Simple secondary 1080p display connected to a laptop with hidpi built in monitor (2560x1600, 16:10 ratio).
OS: Ubuntu 20.04 with Gnome 3.36.3 DE.

Miscellaneous Information:

On the primary hidpi monitor I have enabled fractional scaling.
Issue reproduced on YT and Udemy videos.

[rebron]

@Befo Can you try in Chrome to see if this is a Chromium issue? I don't think this is a Brave specific issue.