My browser / operating system was fine just an hour ago until I saw that when i was doing some coding, a pop-up message appeared to me my screen that my web browser, chrome does not support WebLG.

Here’s a discussion that has some ways to fix it: https://scratch.mit.edu/discuss/topic/624066/
And can you share your browser and OS? If its an older version of Chrome, that’s the likely issue, and you should update it.

Also, it's WebGL not WebLG.

For anyone else having this bug, could you please follow these steps:

1. Quit and relaunch Chrome
2. In your Chrome browser, go to https://webglsamples.org/google-io/2011/100-objects.html and tell me if you see 3D shapes flying around?
3. Same question about the site https://camillemormal.com – do you see photos that scroll smoothly as you drag your mouse?
4. Now try to create a project in Scratch – do you see the “Your browser does not support WebGL” message?
5. Do Scratch-Minion's suggestion: i) click the little “3 vertical dots” icon at the top right of the Chrome browser window and select “Settings” in the drop down menu; then ii) search for “acceleration” at the top of the window; then iii) disable “Use hardware acceleration when available” by dragging the circle on the slider to the left.
6. Repeat steps 1-4; what do you see now?
7. If you still get the “your browser does not support WebGL” message: go to chrome/flags/#ignore-gpu-blocklist and change the setting for “Override software rendering list” to “Enabled”. (Warning: there's a chance that this might cause some glitches or crashing – if you see any problems, go back to chrome/flags/#ignore-gpu-blocklist and set “Override software rendering list” back to what it was before)
8. Repeat steps 1-4; what do you see now?

Thanks!