In 1.47 water/lava updates caused massive spikes in server tick.
But those were quite short lived (under minute usually). And were always caused by player removing a water/lava source from high up. (in quarry generally)
Just your normal flowing liquid didn't cause any abnormal amount of lag. even if it was high waterfall etc.
You are btw not specifying if your lag is fps lag or high server tick time.
fps lag I had so bad during 1.47 that I had to split my base up in smaller sections that were over 200m apart. (mostly caused by lots of engines)