@sasha: Haven't tested it, but, according to release notes, version 21.5 added this function:
https://helpx.adobe.com/indesign/desktop/whats-new/release-notes.html

Also check this thread about issues for that function:
https://community.adobe.com/questions-671/indesign-21-5-remove-all-ai-generated-alt-text-fails-to-detect-and-remove-existing-ai-generated-alt-text-1636668

are there any fixes for this from Adobe without running a random script ?

Greg's script didn't work for me, so I modified chatGPT output, and this worked for me (attachement didn't work, so I'm pasting), it's only looping through linked graphics. Hope it works for you too.
This scripte deletes ALL alt texts, not only AI generated -- please check if this is what you need.
```
var doc = app.activeDocument
var links = doc.links

for (var i = 0; i < links.length; i++) {
var frame = links[i].parent.parent // Link -> Graphic -> Frame
var opts = frame.objectExportOptions

if (
opts.altTextSourceType == SourceType.SOURCE_CUSTOM // checks if custom text is selected option
) {
opts.customAltText = "" // sets custom text to empty string
opts.altTextSourceType = SourceType.SOURCE_XML_STRUCTURE // returns alt text option back to default
}
}
```

Save this text as a jsx file (I called it RemoveAltText.jsx) and put it in your scripts folder. this script seems to be working for me to remove all alt-text from all images in a document.

(all credit where credit is due, i got this script from the facebook InDesign Secrets group, by Ivy Wood and Jean-Claude Tremblay).

#target indesign
#targetengine "session"
function p(o, n) {
var a, i;
if (!o || !o.reflect) return false;
a = o.reflect.properties;
for (i = 0; i < a.length; i++) {
if (a[i].name === n) return true;
}
return false;
}
function main() {
if (app.documents.length === 0) {
alert("No document is open.");
return;
}
var items = app.activeDocument.allPageItems;
var exportOptions;
var i;
for (i = 0; i < items.length; i++) {
if (!p(items[i], "objectExportOptions")) continue;
exportOptions = items[i].objectExportOptions;
if (
p(exportOptions, "altTextSourceType") &&
exportOptions.altTextSourceType === SourceType.SOURCE_CUSTOM
) {
if (p(exportOptions, "customAltText")) {
exportOptions.customAltText = "";
}
exportOptions.altTextSourceType = SourceType.SOURCE_XML_STRUCTURE;
}
}
}
main();