Video fails to play when extension is enabled

[fancybody]

• Browse/System: Firefox 129.0.2 on MacOS Sonoma (some previous versions as well)
• Extension version: 4.1095 (and couple of last versions)
• Bug start date: around first week of August 2024
• Reproducibility: Have NOT seen this bug in multiple windows systems
• Console errors: Nothing out of the ordinary (I have compared it to a identical windows system)
• Other extensions used: Sponsorblock, BlockTube, uBlock Origin, Dark Reader

I have tested 'Improve Youtube!' extension in isolation of other extensions, bug persists. (same for incognito mode)

I use some custom cosmetic filters for uBlock origin.

Custom uBlock Filters

/endscreen.js$script,important,domain=youtube.com
! Remove youtube thumbnails
www.youtube.com##yt-image:style(filter:opacity(0%)!important)
www.youtube.com##ytd-reel-shelf-renderer
www.youtube.com##.yt-img-shadow
! Thumbnail Customization
youtube.com##ytd-thumbnail:style(height: 100px !important)
youtube.com###text-container:style(font-size: 15px !important)
youtube.com###metadata-line:style(font-size: 15px !important; padding-top: 5px !important)
youtube.com###time-status:style(font-size: 10px !important)
youtube.com##ytd-thumbnail-overlay-time-status-renderer:style(right:40% !important; bottom:40% !important; scale: 2 !important)

'Improve Youtube!' settings

'{"add_scroll_to_top":true,"ads":"block_all","ambient_lighting":false,"below_player_loop":false,"below_player_pip":false,"below_player_screenshot":false,"block_av1":false,"block_vp9":false,"channel_compact_theme":false,"channel_default_tab":"/videos","channel_trailer_autoplay":false,"collapse_of_subscription_sections":true,"comments":"hidden","comments_sidebar":false,"day_of_week":false,"description":"expanded","disable_thumbnail_playback":true,"embeddedHidePauseOverlay":true,"embeddedHideShare":true,"embeddedHideYoutubeLogo":true,"forced_play_video_from_the_beginning":false,"forced_theater_mode":true,"header_hide_country_code":true,"header_hide_right_buttons":true,"header_improve_logo":false,"header_position":"hover_on_video_page","header_transparent":false,"hide_animated_thumbnails":true,"hide_clip_button":"hidden","hide_details":false,"hide_dislike_button":"hidden","hide_download_button":"hidden","hide_footer":true,"hide_gradient_bottom":true,"hide_report_button":true,"hide_save_button":"hidden","hide_scroll_for_details":true,"hide_share_button":"hidden","hide_thanks_button":"hidden","hide_voice_search_button":true,"improvedtube_home":"bubbles","improvedtube_youtube_icon":"disabled","it_analyzer":true,"it_blacklist":true,"it_mixer":false,"lastDarkTheme":"dark","lastLightTheme":"default","livechat":"hidden","mini_player":false,"no_page_margin":false,"open_new_tab":false,"player_auto_cinema_mode":true,"player_autoplay":true,"player_autoplay_button":true,"player_autoplay_disable":false,"player_cinema_mode_button":false,"player_crop_chapter_titles":false,"player_fit_to_win_button":true,"player_forced_volume":true,"player_hamburger_button":false,"player_hide_annotations":true,"player_hide_cards":true,"player_hide_endscreen":true,"player_hide_skip_overlay":true,"player_miniplayer_button":true,"player_next_button":true,"player_quality":"hd720","player_repeat_button":true,"player_screen_button":false,"player_settings_button":false,"player_size":"fit_to_window","player_subtitles_button":false,"player_transparent_background":false,"player_view_button":true,"player_volume":60,"playlist_autoplay":true,"playlist_up_next_autoplay":true,"related_videos":"hidden","remove_related_search_results":true,"scroll_bar":"hidden","shortcut_decrease_playback_speed":{"alt":false,"ctrl":false,"shift":true,"keys":{"188":{"code":"Comma","key":"<"}},"wheel":0},"shortcut_increase_playback_speed":{"alt":false,"ctrl":false,"shift":true,"keys":{"190":{"code":"Period","key":">"}},"wheel":0},"shortcut_quality_1080p":{"alt":true,"shift":true,"keys":{"88":{"code":"KeyX","key":"X"}}},"shortcut_quality_720p":{"alt":true,"keys":{"88":{"code":"KeyX","key":"x"}}},"shortcuts_playback_speed_step":0.1,"subscribe":"hidden","theme":"dark","theme_primary_color":[null,null,null],"theme_text_color":[null,null,null],"title_version":true,"up_next_autoplay":false,"youtubeDetailButtons":"normal","youtube_home_page":"search"}'

Bug Demo

(also, see that the description is NOT visible when the bug occurs)

View-Source of the video in the bug demo