Showtime Image Gallery, image editing screen freezes

Hello Lefteris,
Everything fine I hope and enjoying holiday?
On my clients site I'm using Showtime Image Gallery to upload an intro image (as a custom field).
Everything worked fine for quite a while.
Since some days there is an error after uploading an image(at most from 5 august since my client last used it then).
Normally when you upload an image the page redirects to a page where you can resize, cropp, etc. the image.
This screen freezes and you can't do anything anymore.
I've used a backup to set the Joomla version back to 3.10 but that doesn't work.
I also used a different Editor for this user but that also doesn't help.
Maybe you have an idea?
Is this maybe a server related issue?
Thanks and enjoy your holiday!
Greetings Ton

Clients website

I forgot to say, this is all through the frontend.
The backend works fine.

Hello Lefteris,

I just did, thanks!

Hello Lefteris,
I'm using Firefox, the latest version.
As you asked I tested it in Chrome and Edge and there it works just fine.
Then I tried again in Firefox and now it does work.. strange.
I will ask my client if he wants to try again and let me know if it works again on his side.
Thanks!
Greetings, Ton