Tor leaking info?

I was using Tor 8.5.3 with windows 10, and I also had a Mozilla Firefox window open in addition to Tor. Tor security level was set to "safest".

In Mozilla Fireox, I had just done a search for a word using DuckDuckgo, and that word was still populated in that firefox search window.

When i clicked on an unrelated link using Tor to a "Matrix" download page, I noticed that my search term that I had left in the duckduckgo search window in Mozilla Firefox, was now written in the bottom of my Tor Browser window, below the Matrix item I had clicked on.

How did this cross-application leak occur between regular Firefox and TOR? The Matrix link was totally unrelated to any results of my duckduckgo search in Firefox.

Trac:
Username: TorUser777