Random chars appearing in Date/Time output

Question

I am creating the params for an API URL Param Query, and I require a variable that represents 24 hours in the past. Which I have stored below.

 def date_time
  now = DateTime.now
  @past_time =  (Time.new - 1.days).to_s(:db)
 end

Output => "2021-11-28 18:39:02"

I then use this URL in my API, but when printing out the URL I see that a '20' has appeared before the hour portion of Time. I can't figure out what and why causes this change, any ideas?

Output with problem digits bolded:

    def url_param_creator
       url = URI("#{Settings.zendesk.url}/search.json?query=type:ticket status:closed updated<#{@past_time}") 
       puts url
    end

=>  https://******.zendesk.com/api/v2/search.json?query=type:ticket%20status:closed%20updated%3CMon,%2029%20Nov%202021%2017:20:03>