OpenLayers - No touch events on WebKit browsers - webkit

Question

Unfortunately, the events do not work for some WebKit browsers on mobile devices.
There seems to be a problem with the touch-event.
OpenLayers versions: 6.4.3 and 6.5.0
Browsers it does not work with:
Miui Browser 71:
Mozilla/5.0 (Linux; U; Android 10; de-de; Redmi Note 8 Pro Build/QP1A.190711.020) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/71.0.3578.141 Mobile Safari/537.36 XiaoMi/MiuiBrowser/12.8.3-gn
Miui Browser 79:
Mozilla/5.0 (Linux; U; Android 10; de-de; Redmi Note 8 Pro Build/QP1A.190711.020) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/79.0.3945.147 Mobile Safari/537.36 XiaoMi/MiuiBrowser/12.10.8-gn
Safari 12:
Mozilla/5.0 (iPad; CPU OS 12_5 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/12.1.2 Mobile/15E148 Safari/604.1
You can try it on this website: https://wp-osm-plugin.hyumika.com/map-with-one-html-popup-marker-in-wordpress/ (you cannot click on the marker, drag or pinch)
With Chrome and Firefox it works, but with the WebKit browsers, I get no console output:
a_MapObj.on('singleclick', function(e) {
console.log('singleclick');
});
a_MapObj.on('click', function(e) {
console.log('click');
});
a_MapObj.on('dblclick', function(e) {
console.log('dblclick');
});
a_MapObj.on('error', function(e) {
console.log('error :' + e);
});
a_MapObj.on('moveend', function(e) {
console.log('moveend');
});
a_MapObj.on('movestart', function(e) {
console.log('movestart');
});
a_MapObj.on('pointermove', function(e) {
console.log('pointermove');
});
a_MapObj.on('pointerdrag', function(e) {
console.log('pointerdrag');
});
Could you please help me to fix this?
Thanks a lot & regards,
Mark