Huh...Incognito worked.
So I went back to my regular Chrome and I started deleting addons 1 by 1, refreshing in between, and I still get the error. I turned off "Enable experimental features" and still get this error. I can hop back to an old version of C3 and the error goes away.
On the incognito, I started installing all my addons (only about 3 addons that I use), refreshing in between, and it worked fine, no errors. I applied the theme I use, refreshed, no errors.
At least that's likely an easy quick fix for me, just clear my cache and start over. I use Chrome only for C3 so it's super easy for me, but I wonder if anyone else will get the same error (usually I update to beta for months and months and never had errors appear like this).
Sorry for not going through the normal bug report route - I was trying to be super speedy thinking that it might be a "hotfix" moment.
If there's nothing else you'd like me to try, I will clear my Chrome cache and try out the new beta :)
EDIT: I took screenshot of the console (I have no addons in C3 at this point) between r278 and r276.2. Only slight difference, but just in case it's useful:
drive.google.com/file/d/1kQh6gzqs9QYVvSqV124YeZdi8MqeWuJ4/view
Platform information
Browser: Chrome
Browser version: 96.0.4664.110
Browser engine: Chromium
Context: browser
Operating system: Windows
Operating system version: 10
Device type: desktop
Device pixel ratio: 1
Logical CPU cores: 12
Approx. device memory: 8 GB
User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/96.0.4664.110 Safari/537.36
C3 release: r278 (beta)
Language setting: en-US
Local storage
Storage quota (approx): 279 gb
Storage usage (approx): 168 mb (0.1%)
Persistant storage: No
Browser support notes
This list contains missing features that are not required, but could improve performance or user experience if supported.
Nothing is missing. Everything is OK!
WebGL information
Version string: WebGL 2.0 (OpenGL ES 3.0 Chromium)
Numeric version: 2
Supports NPOT textures: yes
Supports GPU profiling: yes
Supports highp precision: yes
Vendor: Google Inc. (NVIDIA)
Renderer: ANGLE (NVIDIA, NVIDIA GeForce RTX 2060 Direct3D11 vs_5_0 ps_5_0, D3D11-30.0.14.9729)
Major performance caveat: no
Maximum texture size: 16384
Point size range: 1 to 1024
Extensions:
EXT_color_buffer_float
EXT_color_buffer_half_float
EXT_disjoint_timer_query_webgl2
EXT_float_blend
EXT_texture_compression_bptc
EXT_texture_compression_rgtc
EXT_texture_filter_anisotropic
EXT_texture_norm16
KHR_parallel_shader_compile
OES_texture_float_linear
WEBGL_compressed_texture_s3tc
WEBGL_compressed_texture_s3tc_srgb
WEBGL_debug_renderer_info
WEBGL_debug_shaders
WEBGL_lose_context
WEBGL_multi_draw
OVR_multiview2
Audio information
System sample rate: 48000 Hz
Output channels: 2
Output interpretation: speakers
Supported decode formats:
WebM Opus (audio/webm; codecs=opus)
Ogg Opus (audio/ogg; codecs=opus)
WebM Vorbis (audio/webm; codecs=vorbis)
Ogg Vorbis (audio/ogg; codecs=vorbis)
MPEG-4 AAC (audio/mp4; codecs=mp4a.40.5)
MP3 (audio/mpeg)
FLAC (audio/flac)
PCM WAV (audio/wav; codecs=1)
Supported encode formats:
WebM Opus (audio/webm; codecs=opus)
Video information
Supported decode formats:
WebM AV1 (video/webm; codecs=av01.0.00M.08)
MP4 AV1 (video/mp4; codecs=av01.0.00M.08)
WebM VP9 (video/webm; codecs=vp9)
WebM VP8 (video/webm; codecs=vp8)
Ogg Theora (video/ogg; codecs=theora)
H.264 (video/mp4; codecs=avc1.42E01E)
Supported encode formats:
WebM VP9 (video/webm; codecs=vp9)
WebM VP8 (video/webm; codecs=vp8)