Make sure you are not blocking content.

Diagnose Firefox issues using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?

https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop also see https://blog.mozilla.org/security/2021/03/23/introducing-smartblock/

https://support.mozilla.org/en-US/kb/smartblock-enhanced-tracking-protection

Many site issues can be caused by corrupt cookies or cache.

Warning ! ! This will log you out of sites you're logged in to. You may also lose any settings for that website.

• Delete cookies to remove the information websites have stored on your computer {web link}

• How to clear the Firefox cache {web link}

What content would normally be displayed in this cut off window ?

Can you attach a screenshot of how this shows in another browser ?

• https://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem
• use a compressed image type like PNG or JPG to save the screenshot

Is this an iframe (i.e. do you see a This Frame item in the right-click context menu) ?

Can you attach a screenshot of how this shows in another browser ?

Is this an iframe (i.e. do you see a This Frame item in the right-click context menu) ? </blockquote>

Added picture of window.

This is what the HTML inspector.

 <button type="button" class="ui-button ui-corner-all ui-widget ui-button-icon-only ui-dialog-titlebar-close" style="border: medium none;" id="flex-modal-pos-ack-layer-modalClose" href="javascript:void(0);">close  layer: You’re ready to download transactions to Quicken or QuickBooks</button>

I found Avast SafePrice | Comparison, deals, coupons add-on is causing the problem. Not even a pop-up blocker.

Can you use the Inspector in Firefox to enlarge that window by setting a suitable height via a this element {height:20em !important} CSS rule ?

• https://developer.mozilla.org/en-US/docs/Tools/Page_Inspector/How_to/Examine_and_edit_HTML

If that Continue button is focused then you might be able to close the pop-up via the space bar or enter and continue via the OK button.

That was very good work. Well Done.