Endless requests for empty "files" (svg image data requests)

Tested in local NC15, NC16 and the screenshots here from demo.nextcloud.com

I am using Safari; when I open e.g. the calendar app, there are several requests for “files” never finishing. My local instance only has 3 of them - but the demo.nextcloud.com should be a better reference

not happening on Chrome.
the only difference I could find is the number of data: svg images which seem to load in Chrome but get stuck on Safari

any idea?
because the continuous loading seems to keep the connection active and the Safari/CPU active.

thank you all,