I am able to reproduce it sometimes, when clicking between two screens back and forth very quickly for a couple of times. Not sure if this is related to the transitions. The html shows this:
The body HTML shows this:
<div class="backdrop"></div><div class="loading-container"><div class="loading"><span>Loading</span><br><ion-spinner icon="lines" class="spinner spinner-lines"><svg viewBox="0 0 64 64"><g stroke-width="7" stroke-linecap="round"><line x1="10" x2="10"><animate attributeName="y1" dur="750ms" values="16;18;28;18;16;16" repeatCount="indefinite"></animate><animate attributeName="y2" dur="750ms" values="48;46;36;44;48;48" repeatCount="indefinite"></animate><animate attributeName="stroke-opacity" dur="750ms" values="1;.4;.5;.8;1;1" repeatCount="indefinite"></animate></line><line x1="24" x2="24"><animate attributeName="y1" dur="750ms" values="16;16;18;28;18;16" repeatCount="indefinite"></animate><animate attributeName="y2" dur="750ms" values="48;48;46;36;44;48" repeatCount="indefinite"></animate><animate attributeName="stroke-opacity" dur="750ms" values="1;1;.4;.5;.8;1" repeatCount="indefinite"></animate></line><line x1="38" x2="38"><animate attributeName="y1" dur="750ms" values="18;16;16;18;28;18" repeatCount="indefinite"></animate><animate attributeName="y2" dur="750ms" values="44;48;48;46;36;44" repeatCount="indefinite"></animate><animate attributeName="stroke-opacity" dur="750ms" values=".8;1;1;.4;.5;.8" repeatCount="indefinite"></animate></line><line x1="52" x2="52"><animate attributeName="y1" dur="750ms" values="28;18;16;16;18;28" repeatCount="indefinite"></animate><animate attributeName="y2" dur="750ms" values="36;44;48;48;46;36" repeatCount="indefinite"></animate><animate attributeName="stroke-opacity" dur="750ms" values=".5;.8;1;1;.4;.5" repeatCount="indefinite"></animate></line></g></svg></ion-spinner></div></div><iframe src="gap://ready" style="display: none;"></iframe></body>