On IOS 13, web pages are reloaded frequently

I studied for a few days and didn't solve the problem. I hope to get help.Thanks a lot.

When the number of hotspots exceeds 80, the web page also reloads all the time.
The type of hotspot is text.
When embedpano, html5="css3D".It's going to be a lot better.But i want to use 'prefer+webgl'.

In the following models:
iOS13 iPhone 8 plus, iPhone 11 Pro, iPhone 11 Pro Max
P.S. We use the Krpano version (19.pr-16).

<hotspot name="h12_s" style="wtkp_hotspotstyle_label_text" title="test" ></hotspot>
<style name="wtkp_hotspotstyle_label_text" type="text" css="font-size:26px; text-align:center; color:#fff; padding:0 10px 0px 10px;font-weight:lighter;" bgcolor="0x000000" bgalpha="0.5" bgborder="0 0xFF0000 1" bgshadow="0 1 0 0x1c93fa 1" bgroundedge="22" edge="bottom"/>

Thanks Klaus.
I once used this method, but it didn't work. I think it might be because of cache. This time, I succeeded in using render ='css3d '.

Although it solved my problem, I found another one.
When you move the scene, the hotspot shakes.