I'm back with another update. I continued upping the weight to 177.5kg/390lbs. I failed the set at rep 4 (23 June 2022 Deadlift @ 177.5kg 1x5 (4th rep fail) - YouTube), and tried again only got 1 (23 June 2022 Deadlift @ 177.5kg 1x5 (2nd attempt) - YouTube).
Any thoughts on my technique?