iOS Collabora Online broken: 17sec response time in Writer

Editing document on local device; same whether .odt or .docx; tried with wifi on or off.
When editing text, unusable delay between keypress and screen update, 10 - 17 secs.

Can’t see a version number, but the hashes are:
Online GIT Hash eb73aa348
Core GIT Hash e90143624dba
iPad Pro running iOS 15.6.1