Despite back spasms only manifesting once maybe every 18 months, after many years of them it is very hard to get your mind to trust that you’ll be ok doing squats. As a physio once explained, my back problems are to some extent a central nervous systems training problem.
My lower back felt like it was on the cusp of going into spasm many times during the squats but it seems to have been fine. On the other hand, my lower back was very sore after this workout. Not pain or any indication of injury, but sore enough to result in some discomfort moving around. Likely my technique was breaking down. I need to start recording my lifts for review.