When using custom Search Engine, query is sent lowercased

Repro:

1. Open Settings > Search > Manage Search Engines
2. Add YouTube as an engine
   • Name: YouTube
   • Search URL template: https://www.youtube.com/results?search_query=%s
   • Keyword: y
3. Navigate to y Jack
4. Note that you're directed to https://www.youtube.com/results?search_query=jack

The query is being lowercased before being sent.
Note that this does not happen when simply searching for Jack: you're redirected to something like https://kagi.com/search?q=Jack.

The desired functionality is in Step 4, to be redirected to https://www.youtube.com/results?search_query=Jack, with the original capitalization of the query.

Version 0.99.128.2.1-beta (WebKit 619.1.11.111.2)

Sonoma (14)