I have found this online, a HTML injection - also doesn't work
<!--- Wrap gallery titles on two lines -------------------------->
<!--- Copyright Soundfocus Digital [sf.digital] ----------------->
<!--- Use freely in your code injection. Do NOT re-publish ------>
<script>
window.Squarespace.onInitialize(Y, () => {
var title = document.querySelectorAll('.image-slide-title');
for (var sf = 0; sf < title.length; ++sf) {
var item = title[sf];
item.innerHTML = item.innerText.replace(/#/g, '<br>');
}
});
</script>