Hello,
I have had multiple issues after upgrading Syncfusion Xamarin Forms from version 19.4.0.48 to version 20.3.0.58.
In the former versions I used to assign plain text to .Text property and it used to work. But after upgrading, I have to use .HtmlText property. Otherwise it doesn't work. This is a major breaking change that you should inform to the users of SfRichTextEditor.
Also after spending hours, I found that I should surround the plain text with <html><body>PLAIN TEXT HERE</body></html> to make it work before assigning it to .HtmlText property.
Thanks.