There was a different behavior in HTML5 searching dialog in previous versions. When I was searching for string vyu, the engine searched for items with and without Czech diacritics (version 2021.2.0.2091), which was perfect. Now when I search the the same string, it searches only for items with diacritics (version 2021.2.0.2148). See attached images.
This looks like it might be related to filter settings. The default (when nothing is specified in appsettings) is CaseSensitive=false, AccentSensitive=true. Which does not correspond to the behavior you describe. Did you change the settings? I think this should give you the behavior you want: