Have an support-ticket regarding this matter with ID: 120052924007915 - Powerapps RTF control links not working?
I have a Sharepoint list with a column, multiple rows, RTF data enabled.
In my powerapps i have a FORM so i can save and read data from my sharepoint list, my datasource.
The form have a RTF editor control.
When a user update a record in the datasource using the RTF editor control and adds any hyperlink to a sharepoint site. The hyperlink is changed and the sharepoint.com part of the URL is replaced.
This leads to that it is impossible to let the user add links to Sharepoint sites or documents.
It is however possible to create links to any external sites. Just sharepoint that fails.
This has been confirmed on above support-ticket.
Microsoft support is typing as an answer:
After further investigation on the issue, I was able to reproduce the problem and have discussed with the team, also the issue seems to be a known issue with custom form and PowerApps when using the Rich Text Editor.
When using the default form from SharePoint, the link is not altered and is therefore functional. However, once the SharePoint is modified in PowerApps or in a PowerApps application separate from the SharePoint list, the link is altered. The beginning of the SharePoint address “sharepoint.com” is replaced.