I manage my small lake for weeds, algae etc. I don’t do the actual treatments but work with a local company.
If we did not treat the weeds the lake would be quickly overrun with weeds in all the shallow areas, which would greatly reduce fishable area. We have 2 extremes of people on the lake. Those that never want to see one weed in the lake, and those that want it all natural- no weed control. Most people could care less. I’m about 2/3 of the way to all natural myself, because it’s better for the fishing, but I also have to please those that are in the “ no weed “camp. It’s not easy.
That being said, I have seen 0% reduction of bass in our lake with once a month treatment. When the weeds all die in the winter the fish don’t relate to the weeds because they aren’t there. Fishing becomes tougher. When the weeds come back in late spring, fish immediately start relating to them again.
I am very much against total herbicide control of weeds in lakes but I realistically must allow some control.
Our old lake sprayer,( a resident) got nearly total control of weeds and only sprayed 1-2 times a year. He did it for 25 years without a fish kill. In 2011 he killed all the weeds( they were really bad because he hadn’t sprayed in a year) , the oxygen level tanked, all the big bass and bream died. My wife watched him scooping them up with a net.It took me 3 years to catch a 4 pound bass again. I wanted to wring his neck. He also lied to me about it. The smaller fish generally survived.
Now, our bass population is excellent, and no re stocking was needed. I actually need to cull some out we have so many. And this is with once a month treatment.
It sounds like you can’t do anything about it but try different baits than normal- maybe the fish got used to the same old baits.