This was found during security review when requested for installation, so the extension is not installed on Miraheze yet
Corresponding Miraheze issue tracker task: https://issue-tracker.miraheze.org/T12979

System message: articlefeedbackv5-activity-pane-header
Cause: https://gerrit.wikimedia.org/r/plugins/gitiles/mediawiki/extensions/ArticleFeedbackv5/+/aa0e2e6dfe9e1004d145f2a787b59885688464c5/modules/jquery.articleFeedbackv5/jquery.articleFeedbackv5.special.js#1709
Screenshot:

1. Leave some feedback on a page
2. Go to Special:ArticleFeedbackv5
3. Mark feedback as inappropriate
4. Request oversight on feedback
5. Refresh page
6. Find that comment again
7. View activity

System messages: articlefeedbackv5-bucket?-title
Cause: https://gerrit.wikimedia.org/r/plugins/gitiles/mediawiki/extensions/ArticleFeedbackv5/+/aa0e2e6dfe9e1004d145f2a787b59885688464c5/modules/jquery.articleFeedbackv5/jquery.articleFeedbackv5.js#710
Screenshot:

1. Use ?uselang=x-xss on a page that has feedback enabled

System message: pipe-separator
Cause: https://gerrit.wikimedia.org/r/plugins/gitiles/mediawiki/extensions/ArticleFeedbackv5/+/aa0e2e6dfe9e1004d145f2a787b59885688464c5/modules/jquery.articleFeedbackv5/jquery.articleFeedbackv5.js#1312
Screenshot:

1. Add to common.css:

#siteSub {
    display: block;
}

2. Add to LocalSettings.php:

$wgArticleFeedbackv5LinkBuckets['buckets']['X'] = 0;
$wgArticleFeedbackv5LinkBuckets['buckets']['A'] = 100;

3. Clear your cookies because you're way too lazy to wait for the chosen bucket to expire lol
4. Use ?uselang=x-xss on a page that has feedback enabled

Cause: https://gerrit.wikimedia.org/r/plugins/gitiles/mediawiki/extensions/ArticleFeedbackv5/+/aa0e2e6dfe9e1004d145f2a787b59885688464c5/modules/jquery.articleFeedbackv5/jquery.articleFeedbackv5.js#2030
Screenshot:

1. Add to common.css:

#siteSub {
    display: block;
}

2. Add to LocalSettings.php:

$wgArticleFeedbackv5LinkBuckets['buckets']['X'] = 0;
$wgArticleFeedbackv5LinkBuckets['buckets']['A'] = 100;

3. Add XSS to the system message articlefeedbackv5-disable-preference
4. Clear your cookies because you're way too lazy to wait for the chosen bucket to expire lol
5. Go to a page with feedback enabled
6. Hover over the "Improve this page" link in the site subtitle
7. Click on the subsequent [x]

Cause: https://gerrit.wikimedia.org/r/plugins/gitiles/mediawiki/extensions/ArticleFeedbackv5/+/aa0e2e6dfe9e1004d145f2a787b59885688464c5/modules/jquery.articleFeedbackv5/jquery.articleFeedbackv5.js#2812
Screenshot:

1. Add to LocalSettings.php:

$wgArticleFeedbackv5ThrottleThresholdPostsPerHour = 0;

2. Add XSS to the system message articlefeedbackv5-error-throttled
3. Go to a page with feedback enabled
4. Try to leave some feedback

System message: articlefeedbackv5-activity-feedback-info
Cause: https://gerrit.wikimedia.org/r/plugins/gitiles/mediawiki/extensions/ArticleFeedbackv5/+/aa0e2e6dfe9e1004d145f2a787b59885688464c5/api/ApiViewActivityArticleFeedbackv5.php#106
Screenshot:

1. Leave some feedback on a page
2. Go to Special:ArticleFeedbackv5
3. Mark feedback as inappropriate
4. Request oversight on feedback
5. Refresh page
6. Find that comment again
7. View activity