Debate in the news (and here) seems to center on UK domestic politics and possible procedural shenanigans. But any extension of the negotiating period would require the unanimous consent of the EU27, and a retraction of the Article 50 notification would have to be unequivocal and unconditional and in accordance with national constitutional requirements.
When there is talk about breaks in the EU27 unified negotiating position, it tends to be speculation (or wishful thinking) that one of the governments might give in to UK demands, but that is not the only way the EU27 unity could unravel.
I do recall news reports in March that Farage and other Brexiteers were lobbying some EU27 governments for a veto on any extension. Hungary and Italy were mentioned.
Are there recent statements by EU or individual government representatives that they might block an extension, or that they would attach conditions?