Select All (Cmd+a) not working on Firefox for certain websites

Memex extension is interfering with the Select All shortcut on Firefox for certain websites (e.g. Duckduckgo). I'm using Macbook Pro M3 Max

To reproduce my error:

• Start Firefox in clean state (i.e. new install, refresh, or create new profile)

• Search something on Duckduckgo

• Press Cmd+a

What I've tested to conclude Memex extension as the cause:

• Cmd+a on other browsers (without the memex extension) works fine

• Cmd+a on Firefox with any other extensions enabled works fine

• Cmd+a on Firefox with all my preferences enabled works fine

• Cmd+a with Memex extension on Firefox with default Firefox settings and no additional extensions doesn't work

I am, however, able to use Select All manually by clicking through the top menu on my mac (Edit - Select All). I just can't use the Select All shortcut, but I use this shortcut everyday and definitely need it for my productivity. Memex will be rendered unusable for me at the current state.