Redmine

It's looks like this change has something to do with that. It's a diff between 5.1.4 and 6.0.1.

diff --git a/lib/redmine/i18n.rb b/lib/redmine/i18n.rb
index 0fe080f4b..a9cd1dd0d 100644
--- a/lib/redmine/i18n.rb
+++ b/lib/redmine/i18n.rb
@@ -21,6 +21,8 @@ require 'redmine'

 module Redmine
   module I18n
+    include ActionView::Helpers::NumberHelper
+
     def self.included(base)
       base.extend Redmine::I18n
     end
@@ -43,17 +45,17 @@ module Redmine
     end

     def l_or_humanize(s, options={})
-      k = "#{options[:prefix]}#{s}".to_sym
+      k = :"#{options[:prefix]}#{s}" 
       ::I18n.t(k, :default => s.to_s.humanize)
     end

     def l_hours(hours)
-      hours = hours.to_f
+      hours = hours.to_f unless hours.is_a?(Numeric)
       l((hours < 2.0 ? :label_f_hour : :label_f_hour_plural), :value => format_hours(hours))
     end

     def l_hours_short(hours)
-      l(:label_f_hour_short, :value => format_hours(hours.to_f))
+      l(:label_f_hour_short, :value => format_hours(hours.is_a?(Numeric) ? hours : hours.to_f))
     end

     def ll(lang, str, arg=nil)
@@ -90,15 +92,27 @@ module Redmine
     def format_hours(hours)
       return "" if hours.blank?

+      minutes = (hours * 60).round
       if Setting.timespan_format == 'minutes'
-        h = hours.floor
-        m = ((hours - h) * 60).round
+        h, m = minutes.divmod(60)
         "%d:%02d" % [h, m]
       else
-        "%.2f" % hours.to_f
+        number_with_delimiter(sprintf('%.2f', minutes.fdiv(60)), delimiter: nil)
       end
     end

+    # Will consider language specific separator in user input
+    # and normalize them to a unified format to be accepted by Kernel.Float().
+    #
+    # @param value [String] A string represenation of a float value.
+    #
+    # @note The delimiter cannot be used here if it is a decimal point since it
+    #       will clash with the dot separator.
+    def normalize_float(value)
+      separator = ::I18n.t('number.format.separator')
+      value.gsub(/[#{separator}]/, separator => '.')
+    end
+
     def day_name(day)
       ::I18n.t('date.day_names')[day % 7]
     end

I think it is related to the changes made in #40914 or #22024.

The timespan setting in Redmine is set to float (0.75) in both instances.