User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:69.0) Gecko/20100101 Firefox/69.0

Steps to reproduce:

Type a search query that ends with '#' into the Firefox address bar and hit return to search. For example, try the string 'unit test c#'. I have attached a gif of this example.

Actual results:

The '#' character is removed from the end of the search query. In the example given, the search ends up being for 'unit test c' and the resulting URL is https://www.google.com/search?client=firefox-b-d&q=unit+test+c

Expected results:

The '#' character should not have been removed from the search query. The resulting URL in the example should have been https://www.google.com/search?client=firefox-b-d&q=unit+test+c%23

The same behaviour can be observed even if you change the 'Default Search Engine' in Options > Search.