.removeAll() no longer working on devices running iOS 16+ - swiftui

Question

I have the removeAll function in my app. It works on iOS 15.7, but not on iOS 16+.
I've looked at the official developer documentation, and it doesn't mention any changes that could've happened in iOS 16+.
Further searching hasn't brought up any mention of this.
What has changed in iOS16+, that has caused this?
UPDATED QUESTION BELOW:
This method is called when user submits an answer to a question. The user's answer is stored as a string literal variable. The user's answer must be cleared from the screen whether the answer is correct or wrong.
I used another part of the app in iOS16+, which uses removeAll to empty an array. It emptied the array. I now suspect that removeAll should only be used on arrays. The user's answer in the code listing below should be assigned empty double quotes, instead of calling the removeAll method.
func checkAnswer() {
cancelDisabled = true
switchLanguageDisabled = true
attemptFinished = true
answered = true
if replaceApostrophesWithBackSlashes(userAnswer: userAnswer.allowedCharacters(string: userAnswer.trimmingCharacters(in: .whitespacesAndNewlines).lowercased())) == foreignNativeAnswer.allowedCharacters(string: foreignNativeAnswer.trimmingCharacters(in: .whitespacesAndNewlines).lowercased()) {
aurotorial.speak(native: dataOps.removeEverythingInBrackets(nativeWord: nativeWordWithoutBrackets), foreign: dataOps.removeDashes(foreignWord: foreignWordWithoutDashes), language: (testSectionThings?[questionCounter].languageSection?.language)!, changeVoiceSpeed: changeVoiceSpeed ?? 0.25, maxLoops: numberSpeechLoops ?? 1)
updateWordCounters(correct: true)
userAnswer.removeAll()
languageColour = .green
showTapSkip = false
showNextTimeDisabled = true
let englishAnswerFont = UIFont.boldSystemFont(ofSize: 16)
let promptAttributes: [NSAttributedString.Key: Any] = [
.font: englishAnswerFont,
.foregroundColor: UIColor(red: 0, green: 0.7, blue: 0, alpha: 1)
]
languageText = NSAttributedString(string: foreignNativeAnswer, attributes: promptAttributes)
nativeForeignPlaceholder = NSMutableAttributedString(string: NSLocalizedString("Correct answer, well done!", comment: "Correct answer"))
DispatchQueue.main.asyncAfter(deadline: .now() + dataOps.determineTextToSpeechDelay(changeVoiceSpeed: changeVoiceSpeed ?? 0.25, numberForeignCharacters: foreignWordWithoutDashes.count)) {
self.prepareForNextQuestion()
}
} else {
updateWordCounters(correct: false)
yourAnswerPrompt = "Your answer: "
wrongAnswer = "\(userAnswer)"
userAnswer.removeAll()
foreignNativeAnswer.removeAll()
languageColour = .blue
showTapSkip = false
iKnowThisDisabled = false
let wrongAnswerFont = UIFont.boldSystemFont(ofSize: 16)
let wrongAnswerAttributes: [NSAttributedString.Key: Any] = [
.font: wrongAnswerFont,
.foregroundColor: UIColor(red: 0, green: 0, blue: 0.7, alpha: 1)
]
languageText = NSAttributedString(string: foreignNativeAnswer, attributes: wrongAnswerAttributes)
answerDisabled = true
let separator = NSMutableAttributedString(string: " ", attributes: noTestSectionThingsAttributes)
let tapAttributedString = NSMutableAttributedString(string: NSLocalizedString("Tap a blue button, then ", comment: "Answer field tap skip 1"), attributes: noTestSectionThingsAttributes)
let skipImageAttachment = NSTextAttachment()
skipImageAttachment.image = UIImage(named: "skip.png")?.withTintColor(.systemBlue)
let skipImageAttributedString = NSMutableAttributedString(attachment: skipImageAttachment)
let nextQuestionAttributedString = NSMutableAttributedString(string: NSLocalizedString(".", comment: "Answer field tap skip 2"), attributes: noTestSectionThingsAttributes)
let NSMutableAttributedStringArray = [tapAttributedString, skipImageAttributedString, nextQuestionAttributedString]
nativeForeignPlaceholder = NSMutableAttributedStringArray.join(withSeparator: separator)
}
enableHint()
enableSkip()
}