Environment:
Browser / Version: Firefox Nightly 98.0a1 (2022-01-31)
Operating System: Windows 10 Pro

Prerequisites:
ETP - Standard enabled.

Steps to Reproduce:

1. Navigate to https://labodeguitaverde.cl/
2. Dismiss the "Importante" popup (using "X" button or by selecting an option from the drop-down menu)
3. Observe the page.

Expected Behavior:
The page loads correctly and is functional.

Actual Behavior:
An overlay is displayed above the page making in unusable.

Notes:

1. Screenshot attached.
2. The issue is not reproducible with ETP disabled.

Oana, a few of us have tried to reproduce this, and it doesn't happen for us. Could you let us know if there is anything interesting shown in the devtools web console when it breaks for you? Right now it seems likely to be related more to an intermittent JS race condition than to ETP.

Tom, strangely with a clean profile (ETP-Standard) the page loads correctly, but if I change it to ETP-Strict and the back to ETP-Standard, the issue occurs.
If I disable ETP and enable it to ETP-Standard the issue no longer occurs.
I've attached the console logs.

Tested with:
Browser / Version: Firefox Nightly 98.0a1 (2022-02-03)
Operating System: Windows 10 Pro

Odd, I've tried on my systems on today's nightly and I can't reproduce this after viewing the page in Standard, reloading it in Strict, and then reloading it in Standard again (with a clean profile).

I also noticed that the overlay is not always broken in Strict mode if I have the devtools open, so I don't think this is actually related to ETP, but is rather an intermittent race condition in the website's code which ETP might be making more obvious.

I was not able to reproduce the issue, regardless of the status of ETP:

https://prnt.sc/yU6sPcmUYBdp

Tested with:

Browser / Version: Firefox Release 101.0.1 (64-bit)/ Firefox Nightly 103.0a1 (2022-06-22) (64-bit)
Operating System: Windows 10 PRO x64

After confirming with Oana, I will be closing this.