spec:

• Strictly maintain storage order (PR More URLSearchParams improvements #10399)
• forEach() argument type check (PR url: check forEach callback is a function #10905)
• Prototype properties enumerability (issue url: make URLSearchParams properties spec-compliant #10799, PR url: make URLSearchParams properties spec-compliant #11057)
• Constructor accepting a sequence<sequence<USVString>> and record<USVString, USVString> (issue url: extend URLSearchParams constructor (whatwg #175) #10635, PR url: extend URLSearchParams constructor #11060)
• Implement sort() (issue url: add sort() to URLSearchParams #10760, PR url: add urlSearchParams.sort() #11098)
• Normalize to USVString (issue url: Improve WHATWG URLSearchParams spec compliance #9484 (comment), PR url: enforce valid UTF-8 in WHATWG parser #11436)

spec irrelevant:

• Export on url (issue url: export URLSearchParams alongside URL #10761, PR url: export URLSearchParams #10801)
• Documentation (PR doc: add basic documentation for WHATWG URL API #10620)

querystring changes:

• Parsing ampersands (issue url: Improve WHATWG URLSearchParams spec compliance #9484 (comment), issue 'querystring.parse' works a inconsistent way with URLSearchParams(chrome) and python's urlparse.parse_qs #10454, PR querystring, url: repeated '&' in a paramsString will be skipped #10967, PR querystring: fix empty pairs handling #11234)
• Serializing spaces (issue url: Improve WHATWG URLSearchParams spec compliance #9484 (comment), issue url, querystring: web platform tests broken by WHATWG URL implementation #11093, PR url: spec-compliant URLSearchParams serializer #11626)
• Preserve parameter order in parsing

/cc @nodejs/url