It's not too bad, only 56 current issues with WebGL across all platforms:
7 specifically related to Construct 2:
Notable is the one on switching tabs freezing multiplayer games, and the slow/janky scrolling
Edit: Actually digging into this with the search term "Scirra" proves interesting too:
https://bugs.chromium.org/p/chromium/issues/detail?id=666710&q=scirra&sort=-modified&colspec=ID%20Pri%20M%20Stars%20ReleaseBlock%20Component%20Status%20Owner%20Summary%20OS%20Modified
[quote:29wntyds](Scirra)What is the expected behavior?
Animations should always finish playing. There should be 0 boxes left in "pending" state after pressing stop.
What went wrong?
Animations get stuck in "pending" state and don't finish. There are some boxes left in "pending" state after pressing stop.
https://bugs.chromium.org/p/chromium/issues/detail?id=650594&q=scirra&sort=-modified&colspec=ID%20Pri%20M%20Stars%20ReleaseBlock%20Component%20Status%20Owner%20Summary%20OS%20Modified
[quote:29wntyds](Scirra)Please also treat tabs with active WebRTC DataChannel connections as exempt. We've already run in to trouble with hosting multiplayer games in background tabs, as described in issue 676036, and from what it sounds the proposed CPU budget will be far too small to keep processing a game.
https://bugs.chromium.org/p/chromium/issues/detail?id=353072&q=scirra&sort=-modified&colspec=ID%20Pri%20M%20Stars%20ReleaseBlock%20Component%20Status%20Owner%20Summary%20OS%20Modified
[quote:29wntyds](Chromium)We don't have any plans currently to try and make <video> or <audio> loop seamlessly.
https://bugs.chromium.org/p/chromium/issues/detail?id=79180&q=scirra&sort=-modified&colspec=ID%20Pri%20M%20Stars%20ReleaseBlock%20Component%20Status%20Owner%20Summary%20OS%20Modified
[quote:29wntyds](Scirra)Recently CSS grid layout performance has become extremely poor in Canary - even just 40-50 elements can take 500ms to layout.
There's bugs in any software though, let alone one as massive as Chromium (which is compounded by the now even-more-massive reliance on Chromium by Construct 3)