PDF's do not render in CEF (Chrome 100) with disable-site-isolation-trials flag.
32-bit Windows version.
I tested with the official test builds:
Broken in cef_binary_100.0.23+ga1e2187+chromium-100.0.4896.127_windows32_client
Works in cef_binary_101.0.11+g0692cb0+chromium-101.0.4951.34_windows32_beta_client
[0419/153200.988:INFO:CONSOLE(0)] "Unchecked runtime.lastError: Not implemented", source: chrome-extension://mhjfbmdgcfjbbpaeojofohoefgiehjai/index.html (0)
[0419/153203.538:ERROR:browser_info_manager.cc(555)] Timeout of new browser info response for frame 25769803781 [6,5]
The first log also happens in the 101 client, but it works, so I don't think that the first log is the cause.